7517 lines
207 KiB
C
7517 lines
207 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* Swap reorganised 29.12.95, Stephen Tweedie.
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* kswapd added: 7.1.96 sct
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* Removed kswapd_ctl limits, and swap out as many pages as needed
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* to bring the system back to freepages.high: 2.4.97, Rik van Riel.
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* Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
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* Multiqueue VM started 5.8.00, Rik van Riel.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/mm.h>
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#include <linux/sched/mm.h>
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#include <linux/module.h>
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#include <linux/gfp.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/pagemap.h>
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#include <linux/init.h>
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#include <linux/highmem.h>
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#include <linux/vmpressure.h>
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#include <linux/vmstat.h>
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#include <linux/file.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h> /* for buffer_heads_over_limit */
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#include <linux/mm_inline.h>
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#include <linux/backing-dev.h>
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#include <linux/rmap.h>
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#include <linux/topology.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/compaction.h>
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#include <linux/notifier.h>
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/freezer.h>
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#include <linux/memcontrol.h>
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#include <linux/migrate.h>
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#include <linux/delayacct.h>
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#include <linux/sysctl.h>
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#include <linux/memory-tiers.h>
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#include <linux/oom.h>
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#include <linux/pagevec.h>
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#include <linux/prefetch.h>
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#include <linux/printk.h>
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#include <linux/dax.h>
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#include <linux/psi.h>
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#include <linux/pagewalk.h>
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#include <linux/shmem_fs.h>
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#include <linux/ctype.h>
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#include <linux/debugfs.h>
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#include <linux/khugepaged.h>
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#include <linux/rculist_nulls.h>
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#include <linux/random.h>
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#include <asm/tlbflush.h>
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#include <asm/div64.h>
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#include <linux/swapops.h>
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#include <linux/balloon_compaction.h>
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#include <linux/sched/sysctl.h>
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#include "internal.h"
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#include "swap.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/vmscan.h>
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struct scan_control {
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/* How many pages shrink_list() should reclaim */
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unsigned long nr_to_reclaim;
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/*
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* Nodemask of nodes allowed by the caller. If NULL, all nodes
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* are scanned.
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*/
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nodemask_t *nodemask;
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/*
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* The memory cgroup that hit its limit and as a result is the
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* primary target of this reclaim invocation.
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*/
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struct mem_cgroup *target_mem_cgroup;
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/*
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* Scan pressure balancing between anon and file LRUs
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*/
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unsigned long anon_cost;
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unsigned long file_cost;
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/* Can active folios be deactivated as part of reclaim? */
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#define DEACTIVATE_ANON 1
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#define DEACTIVATE_FILE 2
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unsigned int may_deactivate:2;
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unsigned int force_deactivate:1;
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unsigned int skipped_deactivate:1;
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/* Writepage batching in laptop mode; RECLAIM_WRITE */
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unsigned int may_writepage:1;
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/* Can mapped folios be reclaimed? */
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unsigned int may_unmap:1;
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/* Can folios be swapped as part of reclaim? */
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unsigned int may_swap:1;
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/* Proactive reclaim invoked by userspace through memory.reclaim */
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unsigned int proactive:1;
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/*
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* Cgroup memory below memory.low is protected as long as we
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* don't threaten to OOM. If any cgroup is reclaimed at
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* reduced force or passed over entirely due to its memory.low
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* setting (memcg_low_skipped), and nothing is reclaimed as a
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* result, then go back for one more cycle that reclaims the protected
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* memory (memcg_low_reclaim) to avert OOM.
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*/
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unsigned int memcg_low_reclaim:1;
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unsigned int memcg_low_skipped:1;
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unsigned int hibernation_mode:1;
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/* One of the zones is ready for compaction */
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unsigned int compaction_ready:1;
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/* There is easily reclaimable cold cache in the current node */
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unsigned int cache_trim_mode:1;
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/* The file folios on the current node are dangerously low */
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unsigned int file_is_tiny:1;
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/* Always discard instead of demoting to lower tier memory */
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unsigned int no_demotion:1;
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/* Allocation order */
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s8 order;
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/* Scan (total_size >> priority) pages at once */
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s8 priority;
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/* The highest zone to isolate folios for reclaim from */
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s8 reclaim_idx;
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/* This context's GFP mask */
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gfp_t gfp_mask;
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/* Incremented by the number of inactive pages that were scanned */
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unsigned long nr_scanned;
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/* Number of pages freed so far during a call to shrink_zones() */
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unsigned long nr_reclaimed;
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struct {
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unsigned int dirty;
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unsigned int unqueued_dirty;
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unsigned int congested;
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unsigned int writeback;
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unsigned int immediate;
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unsigned int file_taken;
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unsigned int taken;
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} nr;
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/* for recording the reclaimed slab by now */
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struct reclaim_state reclaim_state;
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};
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#ifdef ARCH_HAS_PREFETCHW
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#define prefetchw_prev_lru_folio(_folio, _base, _field) \
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do { \
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if ((_folio)->lru.prev != _base) { \
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struct folio *prev; \
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\
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prev = lru_to_folio(&(_folio->lru)); \
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prefetchw(&prev->_field); \
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} \
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} while (0)
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#else
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#define prefetchw_prev_lru_folio(_folio, _base, _field) do { } while (0)
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#endif
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/*
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* From 0 .. 200. Higher means more swappy.
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*/
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int vm_swappiness = 60;
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#ifdef CONFIG_MEMCG
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/* Returns true for reclaim through cgroup limits or cgroup interfaces. */
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static bool cgroup_reclaim(struct scan_control *sc)
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{
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return sc->target_mem_cgroup;
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}
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/*
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* Returns true for reclaim on the root cgroup. This is true for direct
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* allocator reclaim and reclaim through cgroup interfaces on the root cgroup.
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*/
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static bool root_reclaim(struct scan_control *sc)
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{
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return !sc->target_mem_cgroup || mem_cgroup_is_root(sc->target_mem_cgroup);
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}
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/**
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* writeback_throttling_sane - is the usual dirty throttling mechanism available?
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* @sc: scan_control in question
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*
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* The normal page dirty throttling mechanism in balance_dirty_pages() is
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* completely broken with the legacy memcg and direct stalling in
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* shrink_folio_list() is used for throttling instead, which lacks all the
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* niceties such as fairness, adaptive pausing, bandwidth proportional
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* allocation and configurability.
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*
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* This function tests whether the vmscan currently in progress can assume
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* that the normal dirty throttling mechanism is operational.
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*/
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static bool writeback_throttling_sane(struct scan_control *sc)
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{
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if (!cgroup_reclaim(sc))
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return true;
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#ifdef CONFIG_CGROUP_WRITEBACK
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if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
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return true;
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#endif
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return false;
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}
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#else
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static bool cgroup_reclaim(struct scan_control *sc)
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{
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return false;
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}
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static bool root_reclaim(struct scan_control *sc)
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{
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return true;
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}
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static bool writeback_throttling_sane(struct scan_control *sc)
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{
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return true;
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}
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#endif
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static void set_task_reclaim_state(struct task_struct *task,
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struct reclaim_state *rs)
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{
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/* Check for an overwrite */
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WARN_ON_ONCE(rs && task->reclaim_state);
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/* Check for the nulling of an already-nulled member */
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WARN_ON_ONCE(!rs && !task->reclaim_state);
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task->reclaim_state = rs;
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}
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/*
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* flush_reclaim_state(): add pages reclaimed outside of LRU-based reclaim to
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* scan_control->nr_reclaimed.
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*/
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static void flush_reclaim_state(struct scan_control *sc)
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{
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/*
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* Currently, reclaim_state->reclaimed includes three types of pages
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* freed outside of vmscan:
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* (1) Slab pages.
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* (2) Clean file pages from pruned inodes (on highmem systems).
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* (3) XFS freed buffer pages.
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*
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* For all of these cases, we cannot universally link the pages to a
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* single memcg. For example, a memcg-aware shrinker can free one object
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* charged to the target memcg, causing an entire page to be freed.
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* If we count the entire page as reclaimed from the memcg, we end up
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* overestimating the reclaimed amount (potentially under-reclaiming).
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*
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* Only count such pages for global reclaim to prevent under-reclaiming
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* from the target memcg; preventing unnecessary retries during memcg
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* charging and false positives from proactive reclaim.
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*
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* For uncommon cases where the freed pages were actually mostly
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* charged to the target memcg, we end up underestimating the reclaimed
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* amount. This should be fine. The freed pages will be uncharged
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* anyway, even if they are not counted here properly, and we will be
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* able to make forward progress in charging (which is usually in a
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* retry loop).
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*
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* We can go one step further, and report the uncharged objcg pages in
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* memcg reclaim, to make reporting more accurate and reduce
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* underestimation, but it's probably not worth the complexity for now.
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*/
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if (current->reclaim_state && root_reclaim(sc)) {
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sc->nr_reclaimed += current->reclaim_state->reclaimed;
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current->reclaim_state->reclaimed = 0;
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}
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}
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static bool can_demote(int nid, struct scan_control *sc)
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{
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if (!numa_demotion_enabled)
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return false;
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if (sc && sc->no_demotion)
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return false;
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if (next_demotion_node(nid) == NUMA_NO_NODE)
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return false;
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return true;
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}
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static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg,
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int nid,
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struct scan_control *sc)
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{
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if (memcg == NULL) {
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/*
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* For non-memcg reclaim, is there
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* space in any swap device?
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*/
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if (get_nr_swap_pages() > 0)
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return true;
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} else {
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/* Is the memcg below its swap limit? */
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if (mem_cgroup_get_nr_swap_pages(memcg) > 0)
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return true;
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}
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/*
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* The page can not be swapped.
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*
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* Can it be reclaimed from this node via demotion?
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*/
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return can_demote(nid, sc);
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}
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/*
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* This misses isolated folios which are not accounted for to save counters.
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* As the data only determines if reclaim or compaction continues, it is
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* not expected that isolated folios will be a dominating factor.
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*/
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unsigned long zone_reclaimable_pages(struct zone *zone)
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{
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unsigned long nr;
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nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +
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zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);
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if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL))
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nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +
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zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
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return nr;
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}
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/**
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* lruvec_lru_size - Returns the number of pages on the given LRU list.
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* @lruvec: lru vector
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* @lru: lru to use
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* @zone_idx: zones to consider (use MAX_NR_ZONES - 1 for the whole LRU list)
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*/
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static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,
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int zone_idx)
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{
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unsigned long size = 0;
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int zid;
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for (zid = 0; zid <= zone_idx; zid++) {
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struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
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if (!managed_zone(zone))
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continue;
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if (!mem_cgroup_disabled())
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size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
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else
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size += zone_page_state(zone, NR_ZONE_LRU_BASE + lru);
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}
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return size;
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}
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static unsigned long drop_slab_node(int nid)
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{
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unsigned long freed = 0;
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struct mem_cgroup *memcg = NULL;
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memcg = mem_cgroup_iter(NULL, NULL, NULL);
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do {
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freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
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} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
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return freed;
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}
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void drop_slab(void)
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{
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int nid;
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int shift = 0;
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unsigned long freed;
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do {
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freed = 0;
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for_each_online_node(nid) {
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if (fatal_signal_pending(current))
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return;
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freed += drop_slab_node(nid);
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}
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} while ((freed >> shift++) > 1);
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}
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static int reclaimer_offset(void)
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{
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BUILD_BUG_ON(PGSTEAL_DIRECT - PGSTEAL_KSWAPD !=
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PGDEMOTE_DIRECT - PGDEMOTE_KSWAPD);
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BUILD_BUG_ON(PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD !=
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PGDEMOTE_KHUGEPAGED - PGDEMOTE_KSWAPD);
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BUILD_BUG_ON(PGSTEAL_DIRECT - PGSTEAL_KSWAPD !=
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PGSCAN_DIRECT - PGSCAN_KSWAPD);
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BUILD_BUG_ON(PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD !=
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PGSCAN_KHUGEPAGED - PGSCAN_KSWAPD);
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if (current_is_kswapd())
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return 0;
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if (current_is_khugepaged())
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return PGSTEAL_KHUGEPAGED - PGSTEAL_KSWAPD;
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return PGSTEAL_DIRECT - PGSTEAL_KSWAPD;
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}
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static inline int is_page_cache_freeable(struct folio *folio)
|
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{
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/*
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* A freeable page cache folio is referenced only by the caller
|
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* that isolated the folio, the page cache and optional filesystem
|
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* private data at folio->private.
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||
*/
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return folio_ref_count(folio) - folio_test_private(folio) ==
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1 + folio_nr_pages(folio);
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}
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||
|
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/*
|
||
* We detected a synchronous write error writing a folio out. Probably
|
||
* -ENOSPC. We need to propagate that into the address_space for a subsequent
|
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* fsync(), msync() or close().
|
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*
|
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* The tricky part is that after writepage we cannot touch the mapping: nothing
|
||
* prevents it from being freed up. But we have a ref on the folio and once
|
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* that folio is locked, the mapping is pinned.
|
||
*
|
||
* We're allowed to run sleeping folio_lock() here because we know the caller has
|
||
* __GFP_FS.
|
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*/
|
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static void handle_write_error(struct address_space *mapping,
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struct folio *folio, int error)
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{
|
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folio_lock(folio);
|
||
if (folio_mapping(folio) == mapping)
|
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mapping_set_error(mapping, error);
|
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folio_unlock(folio);
|
||
}
|
||
|
||
static bool skip_throttle_noprogress(pg_data_t *pgdat)
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||
{
|
||
int reclaimable = 0, write_pending = 0;
|
||
int i;
|
||
|
||
/*
|
||
* If kswapd is disabled, reschedule if necessary but do not
|
||
* throttle as the system is likely near OOM.
|
||
*/
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
|
||
return true;
|
||
|
||
/*
|
||
* If there are a lot of dirty/writeback folios then do not
|
||
* throttle as throttling will occur when the folios cycle
|
||
* towards the end of the LRU if still under writeback.
|
||
*/
|
||
for (i = 0; i < MAX_NR_ZONES; i++) {
|
||
struct zone *zone = pgdat->node_zones + i;
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
reclaimable += zone_reclaimable_pages(zone);
|
||
write_pending += zone_page_state_snapshot(zone,
|
||
NR_ZONE_WRITE_PENDING);
|
||
}
|
||
if (2 * write_pending <= reclaimable)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)
|
||
{
|
||
wait_queue_head_t *wqh = &pgdat->reclaim_wait[reason];
|
||
long timeout, ret;
|
||
DEFINE_WAIT(wait);
|
||
|
||
/*
|
||
* Do not throttle user workers, kthreads other than kswapd or
|
||
* workqueues. They may be required for reclaim to make
|
||
* forward progress (e.g. journalling workqueues or kthreads).
|
||
*/
|
||
if (!current_is_kswapd() &&
|
||
current->flags & (PF_USER_WORKER|PF_KTHREAD)) {
|
||
cond_resched();
|
||
return;
|
||
}
|
||
|
||
/*
|
||
* These figures are pulled out of thin air.
|
||
* VMSCAN_THROTTLE_ISOLATED is a transient condition based on too many
|
||
* parallel reclaimers which is a short-lived event so the timeout is
|
||
* short. Failing to make progress or waiting on writeback are
|
||
* potentially long-lived events so use a longer timeout. This is shaky
|
||
* logic as a failure to make progress could be due to anything from
|
||
* writeback to a slow device to excessive referenced folios at the tail
|
||
* of the inactive LRU.
|
||
*/
|
||
switch(reason) {
|
||
case VMSCAN_THROTTLE_WRITEBACK:
|
||
timeout = HZ/10;
|
||
|
||
if (atomic_inc_return(&pgdat->nr_writeback_throttled) == 1) {
|
||
WRITE_ONCE(pgdat->nr_reclaim_start,
|
||
node_page_state(pgdat, NR_THROTTLED_WRITTEN));
|
||
}
|
||
|
||
break;
|
||
case VMSCAN_THROTTLE_CONGESTED:
|
||
fallthrough;
|
||
case VMSCAN_THROTTLE_NOPROGRESS:
|
||
if (skip_throttle_noprogress(pgdat)) {
|
||
cond_resched();
|
||
return;
|
||
}
|
||
|
||
timeout = 1;
|
||
|
||
break;
|
||
case VMSCAN_THROTTLE_ISOLATED:
|
||
timeout = HZ/50;
|
||
break;
|
||
default:
|
||
WARN_ON_ONCE(1);
|
||
timeout = HZ;
|
||
break;
|
||
}
|
||
|
||
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
|
||
ret = schedule_timeout(timeout);
|
||
finish_wait(wqh, &wait);
|
||
|
||
if (reason == VMSCAN_THROTTLE_WRITEBACK)
|
||
atomic_dec(&pgdat->nr_writeback_throttled);
|
||
|
||
trace_mm_vmscan_throttled(pgdat->node_id, jiffies_to_usecs(timeout),
|
||
jiffies_to_usecs(timeout - ret),
|
||
reason);
|
||
}
|
||
|
||
/*
|
||
* Account for folios written if tasks are throttled waiting on dirty
|
||
* folios to clean. If enough folios have been cleaned since throttling
|
||
* started then wakeup the throttled tasks.
|
||
*/
|
||
void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio,
|
||
int nr_throttled)
|
||
{
|
||
unsigned long nr_written;
|
||
|
||
node_stat_add_folio(folio, NR_THROTTLED_WRITTEN);
|
||
|
||
/*
|
||
* This is an inaccurate read as the per-cpu deltas may not
|
||
* be synchronised. However, given that the system is
|
||
* writeback throttled, it is not worth taking the penalty
|
||
* of getting an accurate count. At worst, the throttle
|
||
* timeout guarantees forward progress.
|
||
*/
|
||
nr_written = node_page_state(pgdat, NR_THROTTLED_WRITTEN) -
|
||
READ_ONCE(pgdat->nr_reclaim_start);
|
||
|
||
if (nr_written > SWAP_CLUSTER_MAX * nr_throttled)
|
||
wake_up(&pgdat->reclaim_wait[VMSCAN_THROTTLE_WRITEBACK]);
|
||
}
|
||
|
||
/* possible outcome of pageout() */
|
||
typedef enum {
|
||
/* failed to write folio out, folio is locked */
|
||
PAGE_KEEP,
|
||
/* move folio to the active list, folio is locked */
|
||
PAGE_ACTIVATE,
|
||
/* folio has been sent to the disk successfully, folio is unlocked */
|
||
PAGE_SUCCESS,
|
||
/* folio is clean and locked */
|
||
PAGE_CLEAN,
|
||
} pageout_t;
|
||
|
||
/*
|
||
* pageout is called by shrink_folio_list() for each dirty folio.
|
||
* Calls ->writepage().
|
||
*/
|
||
static pageout_t pageout(struct folio *folio, struct address_space *mapping,
|
||
struct swap_iocb **plug)
|
||
{
|
||
/*
|
||
* If the folio is dirty, only perform writeback if that write
|
||
* will be non-blocking. To prevent this allocation from being
|
||
* stalled by pagecache activity. But note that there may be
|
||
* stalls if we need to run get_block(). We could test
|
||
* PagePrivate for that.
|
||
*
|
||
* If this process is currently in __generic_file_write_iter() against
|
||
* this folio's queue, we can perform writeback even if that
|
||
* will block.
|
||
*
|
||
* If the folio is swapcache, write it back even if that would
|
||
* block, for some throttling. This happens by accident, because
|
||
* swap_backing_dev_info is bust: it doesn't reflect the
|
||
* congestion state of the swapdevs. Easy to fix, if needed.
|
||
*/
|
||
if (!is_page_cache_freeable(folio))
|
||
return PAGE_KEEP;
|
||
if (!mapping) {
|
||
/*
|
||
* Some data journaling orphaned folios can have
|
||
* folio->mapping == NULL while being dirty with clean buffers.
|
||
*/
|
||
if (folio_test_private(folio)) {
|
||
if (try_to_free_buffers(folio)) {
|
||
folio_clear_dirty(folio);
|
||
pr_info("%s: orphaned folio\n", __func__);
|
||
return PAGE_CLEAN;
|
||
}
|
||
}
|
||
return PAGE_KEEP;
|
||
}
|
||
if (mapping->a_ops->writepage == NULL)
|
||
return PAGE_ACTIVATE;
|
||
|
||
if (folio_clear_dirty_for_io(folio)) {
|
||
int res;
|
||
struct writeback_control wbc = {
|
||
.sync_mode = WB_SYNC_NONE,
|
||
.nr_to_write = SWAP_CLUSTER_MAX,
|
||
.range_start = 0,
|
||
.range_end = LLONG_MAX,
|
||
.for_reclaim = 1,
|
||
.swap_plug = plug,
|
||
};
|
||
|
||
folio_set_reclaim(folio);
|
||
res = mapping->a_ops->writepage(&folio->page, &wbc);
|
||
if (res < 0)
|
||
handle_write_error(mapping, folio, res);
|
||
if (res == AOP_WRITEPAGE_ACTIVATE) {
|
||
folio_clear_reclaim(folio);
|
||
return PAGE_ACTIVATE;
|
||
}
|
||
|
||
if (!folio_test_writeback(folio)) {
|
||
/* synchronous write or broken a_ops? */
|
||
folio_clear_reclaim(folio);
|
||
}
|
||
trace_mm_vmscan_write_folio(folio);
|
||
node_stat_add_folio(folio, NR_VMSCAN_WRITE);
|
||
return PAGE_SUCCESS;
|
||
}
|
||
|
||
return PAGE_CLEAN;
|
||
}
|
||
|
||
/*
|
||
* Same as remove_mapping, but if the folio is removed from the mapping, it
|
||
* gets returned with a refcount of 0.
|
||
*/
|
||
static int __remove_mapping(struct address_space *mapping, struct folio *folio,
|
||
bool reclaimed, struct mem_cgroup *target_memcg)
|
||
{
|
||
int refcount;
|
||
void *shadow = NULL;
|
||
|
||
BUG_ON(!folio_test_locked(folio));
|
||
BUG_ON(mapping != folio_mapping(folio));
|
||
|
||
if (!folio_test_swapcache(folio))
|
||
spin_lock(&mapping->host->i_lock);
|
||
xa_lock_irq(&mapping->i_pages);
|
||
/*
|
||
* The non racy check for a busy folio.
|
||
*
|
||
* Must be careful with the order of the tests. When someone has
|
||
* a ref to the folio, it may be possible that they dirty it then
|
||
* drop the reference. So if the dirty flag is tested before the
|
||
* refcount here, then the following race may occur:
|
||
*
|
||
* get_user_pages(&page);
|
||
* [user mapping goes away]
|
||
* write_to(page);
|
||
* !folio_test_dirty(folio) [good]
|
||
* folio_set_dirty(folio);
|
||
* folio_put(folio);
|
||
* !refcount(folio) [good, discard it]
|
||
*
|
||
* [oops, our write_to data is lost]
|
||
*
|
||
* Reversing the order of the tests ensures such a situation cannot
|
||
* escape unnoticed. The smp_rmb is needed to ensure the folio->flags
|
||
* load is not satisfied before that of folio->_refcount.
|
||
*
|
||
* Note that if the dirty flag is always set via folio_mark_dirty,
|
||
* and thus under the i_pages lock, then this ordering is not required.
|
||
*/
|
||
refcount = 1 + folio_nr_pages(folio);
|
||
if (!folio_ref_freeze(folio, refcount))
|
||
goto cannot_free;
|
||
/* note: atomic_cmpxchg in folio_ref_freeze provides the smp_rmb */
|
||
if (unlikely(folio_test_dirty(folio))) {
|
||
folio_ref_unfreeze(folio, refcount);
|
||
goto cannot_free;
|
||
}
|
||
|
||
if (folio_test_swapcache(folio)) {
|
||
swp_entry_t swap = folio->swap;
|
||
|
||
if (reclaimed && !mapping_exiting(mapping))
|
||
shadow = workingset_eviction(folio, target_memcg);
|
||
__delete_from_swap_cache(folio, swap, shadow);
|
||
mem_cgroup_swapout(folio, swap);
|
||
xa_unlock_irq(&mapping->i_pages);
|
||
put_swap_folio(folio, swap);
|
||
} else {
|
||
void (*free_folio)(struct folio *);
|
||
|
||
free_folio = mapping->a_ops->free_folio;
|
||
/*
|
||
* Remember a shadow entry for reclaimed file cache in
|
||
* order to detect refaults, thus thrashing, later on.
|
||
*
|
||
* But don't store shadows in an address space that is
|
||
* already exiting. This is not just an optimization,
|
||
* inode reclaim needs to empty out the radix tree or
|
||
* the nodes are lost. Don't plant shadows behind its
|
||
* back.
|
||
*
|
||
* We also don't store shadows for DAX mappings because the
|
||
* only page cache folios found in these are zero pages
|
||
* covering holes, and because we don't want to mix DAX
|
||
* exceptional entries and shadow exceptional entries in the
|
||
* same address_space.
|
||
*/
|
||
if (reclaimed && folio_is_file_lru(folio) &&
|
||
!mapping_exiting(mapping) && !dax_mapping(mapping))
|
||
shadow = workingset_eviction(folio, target_memcg);
|
||
__filemap_remove_folio(folio, shadow);
|
||
xa_unlock_irq(&mapping->i_pages);
|
||
if (mapping_shrinkable(mapping))
|
||
inode_add_lru(mapping->host);
|
||
spin_unlock(&mapping->host->i_lock);
|
||
|
||
if (free_folio)
|
||
free_folio(folio);
|
||
}
|
||
|
||
return 1;
|
||
|
||
cannot_free:
|
||
xa_unlock_irq(&mapping->i_pages);
|
||
if (!folio_test_swapcache(folio))
|
||
spin_unlock(&mapping->host->i_lock);
|
||
return 0;
|
||
}
|
||
|
||
/**
|
||
* remove_mapping() - Attempt to remove a folio from its mapping.
|
||
* @mapping: The address space.
|
||
* @folio: The folio to remove.
|
||
*
|
||
* If the folio is dirty, under writeback or if someone else has a ref
|
||
* on it, removal will fail.
|
||
* Return: The number of pages removed from the mapping. 0 if the folio
|
||
* could not be removed.
|
||
* Context: The caller should have a single refcount on the folio and
|
||
* hold its lock.
|
||
*/
|
||
long remove_mapping(struct address_space *mapping, struct folio *folio)
|
||
{
|
||
if (__remove_mapping(mapping, folio, false, NULL)) {
|
||
/*
|
||
* Unfreezing the refcount with 1 effectively
|
||
* drops the pagecache ref for us without requiring another
|
||
* atomic operation.
|
||
*/
|
||
folio_ref_unfreeze(folio, 1);
|
||
return folio_nr_pages(folio);
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
/**
|
||
* folio_putback_lru - Put previously isolated folio onto appropriate LRU list.
|
||
* @folio: Folio to be returned to an LRU list.
|
||
*
|
||
* Add previously isolated @folio to appropriate LRU list.
|
||
* The folio may still be unevictable for other reasons.
|
||
*
|
||
* Context: lru_lock must not be held, interrupts must be enabled.
|
||
*/
|
||
void folio_putback_lru(struct folio *folio)
|
||
{
|
||
folio_add_lru(folio);
|
||
folio_put(folio); /* drop ref from isolate */
|
||
}
|
||
|
||
enum folio_references {
|
||
FOLIOREF_RECLAIM,
|
||
FOLIOREF_RECLAIM_CLEAN,
|
||
FOLIOREF_KEEP,
|
||
FOLIOREF_ACTIVATE,
|
||
};
|
||
|
||
static enum folio_references folio_check_references(struct folio *folio,
|
||
struct scan_control *sc)
|
||
{
|
||
int referenced_ptes, referenced_folio;
|
||
unsigned long vm_flags;
|
||
|
||
referenced_ptes = folio_referenced(folio, 1, sc->target_mem_cgroup,
|
||
&vm_flags);
|
||
referenced_folio = folio_test_clear_referenced(folio);
|
||
|
||
/*
|
||
* The supposedly reclaimable folio was found to be in a VM_LOCKED vma.
|
||
* Let the folio, now marked Mlocked, be moved to the unevictable list.
|
||
*/
|
||
if (vm_flags & VM_LOCKED)
|
||
return FOLIOREF_ACTIVATE;
|
||
|
||
/* rmap lock contention: rotate */
|
||
if (referenced_ptes == -1)
|
||
return FOLIOREF_KEEP;
|
||
|
||
if (referenced_ptes) {
|
||
/*
|
||
* All mapped folios start out with page table
|
||
* references from the instantiating fault, so we need
|
||
* to look twice if a mapped file/anon folio is used more
|
||
* than once.
|
||
*
|
||
* Mark it and spare it for another trip around the
|
||
* inactive list. Another page table reference will
|
||
* lead to its activation.
|
||
*
|
||
* Note: the mark is set for activated folios as well
|
||
* so that recently deactivated but used folios are
|
||
* quickly recovered.
|
||
*/
|
||
folio_set_referenced(folio);
|
||
|
||
if (referenced_folio || referenced_ptes > 1)
|
||
return FOLIOREF_ACTIVATE;
|
||
|
||
/*
|
||
* Activate file-backed executable folios after first usage.
|
||
*/
|
||
if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio))
|
||
return FOLIOREF_ACTIVATE;
|
||
|
||
return FOLIOREF_KEEP;
|
||
}
|
||
|
||
/* Reclaim if clean, defer dirty folios to writeback */
|
||
if (referenced_folio && folio_is_file_lru(folio))
|
||
return FOLIOREF_RECLAIM_CLEAN;
|
||
|
||
return FOLIOREF_RECLAIM;
|
||
}
|
||
|
||
/* Check if a folio is dirty or under writeback */
|
||
static void folio_check_dirty_writeback(struct folio *folio,
|
||
bool *dirty, bool *writeback)
|
||
{
|
||
struct address_space *mapping;
|
||
|
||
/*
|
||
* Anonymous folios are not handled by flushers and must be written
|
||
* from reclaim context. Do not stall reclaim based on them.
|
||
* MADV_FREE anonymous folios are put into inactive file list too.
|
||
* They could be mistakenly treated as file lru. So further anon
|
||
* test is needed.
|
||
*/
|
||
if (!folio_is_file_lru(folio) ||
|
||
(folio_test_anon(folio) && !folio_test_swapbacked(folio))) {
|
||
*dirty = false;
|
||
*writeback = false;
|
||
return;
|
||
}
|
||
|
||
/* By default assume that the folio flags are accurate */
|
||
*dirty = folio_test_dirty(folio);
|
||
*writeback = folio_test_writeback(folio);
|
||
|
||
/* Verify dirty/writeback state if the filesystem supports it */
|
||
if (!folio_test_private(folio))
|
||
return;
|
||
|
||
mapping = folio_mapping(folio);
|
||
if (mapping && mapping->a_ops->is_dirty_writeback)
|
||
mapping->a_ops->is_dirty_writeback(folio, dirty, writeback);
|
||
}
|
||
|
||
static struct folio *alloc_demote_folio(struct folio *src,
|
||
unsigned long private)
|
||
{
|
||
struct folio *dst;
|
||
nodemask_t *allowed_mask;
|
||
struct migration_target_control *mtc;
|
||
|
||
mtc = (struct migration_target_control *)private;
|
||
|
||
allowed_mask = mtc->nmask;
|
||
/*
|
||
* make sure we allocate from the target node first also trying to
|
||
* demote or reclaim pages from the target node via kswapd if we are
|
||
* low on free memory on target node. If we don't do this and if
|
||
* we have free memory on the slower(lower) memtier, we would start
|
||
* allocating pages from slower(lower) memory tiers without even forcing
|
||
* a demotion of cold pages from the target memtier. This can result
|
||
* in the kernel placing hot pages in slower(lower) memory tiers.
|
||
*/
|
||
mtc->nmask = NULL;
|
||
mtc->gfp_mask |= __GFP_THISNODE;
|
||
dst = alloc_migration_target(src, (unsigned long)mtc);
|
||
if (dst)
|
||
return dst;
|
||
|
||
mtc->gfp_mask &= ~__GFP_THISNODE;
|
||
mtc->nmask = allowed_mask;
|
||
|
||
return alloc_migration_target(src, (unsigned long)mtc);
|
||
}
|
||
|
||
/*
|
||
* Take folios on @demote_folios and attempt to demote them to another node.
|
||
* Folios which are not demoted are left on @demote_folios.
|
||
*/
|
||
static unsigned int demote_folio_list(struct list_head *demote_folios,
|
||
struct pglist_data *pgdat)
|
||
{
|
||
int target_nid = next_demotion_node(pgdat->node_id);
|
||
unsigned int nr_succeeded;
|
||
nodemask_t allowed_mask;
|
||
|
||
struct migration_target_control mtc = {
|
||
/*
|
||
* Allocate from 'node', or fail quickly and quietly.
|
||
* When this happens, 'page' will likely just be discarded
|
||
* instead of migrated.
|
||
*/
|
||
.gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | __GFP_NOWARN |
|
||
__GFP_NOMEMALLOC | GFP_NOWAIT,
|
||
.nid = target_nid,
|
||
.nmask = &allowed_mask
|
||
};
|
||
|
||
if (list_empty(demote_folios))
|
||
return 0;
|
||
|
||
if (target_nid == NUMA_NO_NODE)
|
||
return 0;
|
||
|
||
node_get_allowed_targets(pgdat, &allowed_mask);
|
||
|
||
/* Demotion ignores all cpuset and mempolicy settings */
|
||
migrate_pages(demote_folios, alloc_demote_folio, NULL,
|
||
(unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION,
|
||
&nr_succeeded);
|
||
|
||
mod_node_page_state(pgdat, PGDEMOTE_KSWAPD + reclaimer_offset(),
|
||
nr_succeeded);
|
||
|
||
return nr_succeeded;
|
||
}
|
||
|
||
static bool may_enter_fs(struct folio *folio, gfp_t gfp_mask)
|
||
{
|
||
if (gfp_mask & __GFP_FS)
|
||
return true;
|
||
if (!folio_test_swapcache(folio) || !(gfp_mask & __GFP_IO))
|
||
return false;
|
||
/*
|
||
* We can "enter_fs" for swap-cache with only __GFP_IO
|
||
* providing this isn't SWP_FS_OPS.
|
||
* ->flags can be updated non-atomicially (scan_swap_map_slots),
|
||
* but that will never affect SWP_FS_OPS, so the data_race
|
||
* is safe.
|
||
*/
|
||
return !data_race(folio_swap_flags(folio) & SWP_FS_OPS);
|
||
}
|
||
|
||
/*
|
||
* shrink_folio_list() returns the number of reclaimed pages
|
||
*/
|
||
static unsigned int shrink_folio_list(struct list_head *folio_list,
|
||
struct pglist_data *pgdat, struct scan_control *sc,
|
||
struct reclaim_stat *stat, bool ignore_references)
|
||
{
|
||
LIST_HEAD(ret_folios);
|
||
LIST_HEAD(free_folios);
|
||
LIST_HEAD(demote_folios);
|
||
unsigned int nr_reclaimed = 0;
|
||
unsigned int pgactivate = 0;
|
||
bool do_demote_pass;
|
||
struct swap_iocb *plug = NULL;
|
||
|
||
memset(stat, 0, sizeof(*stat));
|
||
cond_resched();
|
||
do_demote_pass = can_demote(pgdat->node_id, sc);
|
||
|
||
retry:
|
||
while (!list_empty(folio_list)) {
|
||
struct address_space *mapping;
|
||
struct folio *folio;
|
||
enum folio_references references = FOLIOREF_RECLAIM;
|
||
bool dirty, writeback;
|
||
unsigned int nr_pages;
|
||
|
||
cond_resched();
|
||
|
||
folio = lru_to_folio(folio_list);
|
||
list_del(&folio->lru);
|
||
|
||
if (!folio_trylock(folio))
|
||
goto keep;
|
||
|
||
VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
|
||
|
||
nr_pages = folio_nr_pages(folio);
|
||
|
||
/* Account the number of base pages */
|
||
sc->nr_scanned += nr_pages;
|
||
|
||
if (unlikely(!folio_evictable(folio)))
|
||
goto activate_locked;
|
||
|
||
if (!sc->may_unmap && folio_mapped(folio))
|
||
goto keep_locked;
|
||
|
||
/* folio_update_gen() tried to promote this page? */
|
||
if (lru_gen_enabled() && !ignore_references &&
|
||
folio_mapped(folio) && folio_test_referenced(folio))
|
||
goto keep_locked;
|
||
|
||
/*
|
||
* The number of dirty pages determines if a node is marked
|
||
* reclaim_congested. kswapd will stall and start writing
|
||
* folios if the tail of the LRU is all dirty unqueued folios.
|
||
*/
|
||
folio_check_dirty_writeback(folio, &dirty, &writeback);
|
||
if (dirty || writeback)
|
||
stat->nr_dirty += nr_pages;
|
||
|
||
if (dirty && !writeback)
|
||
stat->nr_unqueued_dirty += nr_pages;
|
||
|
||
/*
|
||
* Treat this folio as congested if folios are cycling
|
||
* through the LRU so quickly that the folios marked
|
||
* for immediate reclaim are making it to the end of
|
||
* the LRU a second time.
|
||
*/
|
||
if (writeback && folio_test_reclaim(folio))
|
||
stat->nr_congested += nr_pages;
|
||
|
||
/*
|
||
* If a folio at the tail of the LRU is under writeback, there
|
||
* are three cases to consider.
|
||
*
|
||
* 1) If reclaim is encountering an excessive number
|
||
* of folios under writeback and this folio has both
|
||
* the writeback and reclaim flags set, then it
|
||
* indicates that folios are being queued for I/O but
|
||
* are being recycled through the LRU before the I/O
|
||
* can complete. Waiting on the folio itself risks an
|
||
* indefinite stall if it is impossible to writeback
|
||
* the folio due to I/O error or disconnected storage
|
||
* so instead note that the LRU is being scanned too
|
||
* quickly and the caller can stall after the folio
|
||
* list has been processed.
|
||
*
|
||
* 2) Global or new memcg reclaim encounters a folio that is
|
||
* not marked for immediate reclaim, or the caller does not
|
||
* have __GFP_FS (or __GFP_IO if it's simply going to swap,
|
||
* not to fs). In this case mark the folio for immediate
|
||
* reclaim and continue scanning.
|
||
*
|
||
* Require may_enter_fs() because we would wait on fs, which
|
||
* may not have submitted I/O yet. And the loop driver might
|
||
* enter reclaim, and deadlock if it waits on a folio for
|
||
* which it is needed to do the write (loop masks off
|
||
* __GFP_IO|__GFP_FS for this reason); but more thought
|
||
* would probably show more reasons.
|
||
*
|
||
* 3) Legacy memcg encounters a folio that already has the
|
||
* reclaim flag set. memcg does not have any dirty folio
|
||
* throttling so we could easily OOM just because too many
|
||
* folios are in writeback and there is nothing else to
|
||
* reclaim. Wait for the writeback to complete.
|
||
*
|
||
* In cases 1) and 2) we activate the folios to get them out of
|
||
* the way while we continue scanning for clean folios on the
|
||
* inactive list and refilling from the active list. The
|
||
* observation here is that waiting for disk writes is more
|
||
* expensive than potentially causing reloads down the line.
|
||
* Since they're marked for immediate reclaim, they won't put
|
||
* memory pressure on the cache working set any longer than it
|
||
* takes to write them to disk.
|
||
*/
|
||
if (folio_test_writeback(folio)) {
|
||
/* Case 1 above */
|
||
if (current_is_kswapd() &&
|
||
folio_test_reclaim(folio) &&
|
||
test_bit(PGDAT_WRITEBACK, &pgdat->flags)) {
|
||
stat->nr_immediate += nr_pages;
|
||
goto activate_locked;
|
||
|
||
/* Case 2 above */
|
||
} else if (writeback_throttling_sane(sc) ||
|
||
!folio_test_reclaim(folio) ||
|
||
!may_enter_fs(folio, sc->gfp_mask)) {
|
||
/*
|
||
* This is slightly racy -
|
||
* folio_end_writeback() might have
|
||
* just cleared the reclaim flag, then
|
||
* setting the reclaim flag here ends up
|
||
* interpreted as the readahead flag - but
|
||
* that does not matter enough to care.
|
||
* What we do want is for this folio to
|
||
* have the reclaim flag set next time
|
||
* memcg reclaim reaches the tests above,
|
||
* so it will then wait for writeback to
|
||
* avoid OOM; and it's also appropriate
|
||
* in global reclaim.
|
||
*/
|
||
folio_set_reclaim(folio);
|
||
stat->nr_writeback += nr_pages;
|
||
goto activate_locked;
|
||
|
||
/* Case 3 above */
|
||
} else {
|
||
folio_unlock(folio);
|
||
folio_wait_writeback(folio);
|
||
/* then go back and try same folio again */
|
||
list_add_tail(&folio->lru, folio_list);
|
||
continue;
|
||
}
|
||
}
|
||
|
||
if (!ignore_references)
|
||
references = folio_check_references(folio, sc);
|
||
|
||
switch (references) {
|
||
case FOLIOREF_ACTIVATE:
|
||
goto activate_locked;
|
||
case FOLIOREF_KEEP:
|
||
stat->nr_ref_keep += nr_pages;
|
||
goto keep_locked;
|
||
case FOLIOREF_RECLAIM:
|
||
case FOLIOREF_RECLAIM_CLEAN:
|
||
; /* try to reclaim the folio below */
|
||
}
|
||
|
||
/*
|
||
* Before reclaiming the folio, try to relocate
|
||
* its contents to another node.
|
||
*/
|
||
if (do_demote_pass &&
|
||
(thp_migration_supported() || !folio_test_large(folio))) {
|
||
list_add(&folio->lru, &demote_folios);
|
||
folio_unlock(folio);
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* Anonymous process memory has backing store?
|
||
* Try to allocate it some swap space here.
|
||
* Lazyfree folio could be freed directly
|
||
*/
|
||
if (folio_test_anon(folio) && folio_test_swapbacked(folio)) {
|
||
if (!folio_test_swapcache(folio)) {
|
||
if (!(sc->gfp_mask & __GFP_IO))
|
||
goto keep_locked;
|
||
if (folio_maybe_dma_pinned(folio))
|
||
goto keep_locked;
|
||
if (folio_test_large(folio)) {
|
||
/* cannot split folio, skip it */
|
||
if (!can_split_folio(folio, NULL))
|
||
goto activate_locked;
|
||
/*
|
||
* Split folios without a PMD map right
|
||
* away. Chances are some or all of the
|
||
* tail pages can be freed without IO.
|
||
*/
|
||
if (!folio_entire_mapcount(folio) &&
|
||
split_folio_to_list(folio,
|
||
folio_list))
|
||
goto activate_locked;
|
||
}
|
||
if (!add_to_swap(folio)) {
|
||
if (!folio_test_large(folio))
|
||
goto activate_locked_split;
|
||
/* Fallback to swap normal pages */
|
||
if (split_folio_to_list(folio,
|
||
folio_list))
|
||
goto activate_locked;
|
||
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
||
count_memcg_folio_events(folio, THP_SWPOUT_FALLBACK, 1);
|
||
count_vm_event(THP_SWPOUT_FALLBACK);
|
||
#endif
|
||
if (!add_to_swap(folio))
|
||
goto activate_locked_split;
|
||
}
|
||
}
|
||
} else if (folio_test_swapbacked(folio) &&
|
||
folio_test_large(folio)) {
|
||
/* Split shmem folio */
|
||
if (split_folio_to_list(folio, folio_list))
|
||
goto keep_locked;
|
||
}
|
||
|
||
/*
|
||
* If the folio was split above, the tail pages will make
|
||
* their own pass through this function and be accounted
|
||
* then.
|
||
*/
|
||
if ((nr_pages > 1) && !folio_test_large(folio)) {
|
||
sc->nr_scanned -= (nr_pages - 1);
|
||
nr_pages = 1;
|
||
}
|
||
|
||
/*
|
||
* The folio is mapped into the page tables of one or more
|
||
* processes. Try to unmap it here.
|
||
*/
|
||
if (folio_mapped(folio)) {
|
||
enum ttu_flags flags = TTU_BATCH_FLUSH;
|
||
bool was_swapbacked = folio_test_swapbacked(folio);
|
||
|
||
if (folio_test_pmd_mappable(folio))
|
||
flags |= TTU_SPLIT_HUGE_PMD;
|
||
|
||
try_to_unmap(folio, flags);
|
||
if (folio_mapped(folio)) {
|
||
stat->nr_unmap_fail += nr_pages;
|
||
if (!was_swapbacked &&
|
||
folio_test_swapbacked(folio))
|
||
stat->nr_lazyfree_fail += nr_pages;
|
||
goto activate_locked;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Folio is unmapped now so it cannot be newly pinned anymore.
|
||
* No point in trying to reclaim folio if it is pinned.
|
||
* Furthermore we don't want to reclaim underlying fs metadata
|
||
* if the folio is pinned and thus potentially modified by the
|
||
* pinning process as that may upset the filesystem.
|
||
*/
|
||
if (folio_maybe_dma_pinned(folio))
|
||
goto activate_locked;
|
||
|
||
mapping = folio_mapping(folio);
|
||
if (folio_test_dirty(folio)) {
|
||
/*
|
||
* Only kswapd can writeback filesystem folios
|
||
* to avoid risk of stack overflow. But avoid
|
||
* injecting inefficient single-folio I/O into
|
||
* flusher writeback as much as possible: only
|
||
* write folios when we've encountered many
|
||
* dirty folios, and when we've already scanned
|
||
* the rest of the LRU for clean folios and see
|
||
* the same dirty folios again (with the reclaim
|
||
* flag set).
|
||
*/
|
||
if (folio_is_file_lru(folio) &&
|
||
(!current_is_kswapd() ||
|
||
!folio_test_reclaim(folio) ||
|
||
!test_bit(PGDAT_DIRTY, &pgdat->flags))) {
|
||
/*
|
||
* Immediately reclaim when written back.
|
||
* Similar in principle to folio_deactivate()
|
||
* except we already have the folio isolated
|
||
* and know it's dirty
|
||
*/
|
||
node_stat_mod_folio(folio, NR_VMSCAN_IMMEDIATE,
|
||
nr_pages);
|
||
folio_set_reclaim(folio);
|
||
|
||
goto activate_locked;
|
||
}
|
||
|
||
if (references == FOLIOREF_RECLAIM_CLEAN)
|
||
goto keep_locked;
|
||
if (!may_enter_fs(folio, sc->gfp_mask))
|
||
goto keep_locked;
|
||
if (!sc->may_writepage)
|
||
goto keep_locked;
|
||
|
||
/*
|
||
* Folio is dirty. Flush the TLB if a writable entry
|
||
* potentially exists to avoid CPU writes after I/O
|
||
* starts and then write it out here.
|
||
*/
|
||
try_to_unmap_flush_dirty();
|
||
switch (pageout(folio, mapping, &plug)) {
|
||
case PAGE_KEEP:
|
||
goto keep_locked;
|
||
case PAGE_ACTIVATE:
|
||
goto activate_locked;
|
||
case PAGE_SUCCESS:
|
||
stat->nr_pageout += nr_pages;
|
||
|
||
if (folio_test_writeback(folio))
|
||
goto keep;
|
||
if (folio_test_dirty(folio))
|
||
goto keep;
|
||
|
||
/*
|
||
* A synchronous write - probably a ramdisk. Go
|
||
* ahead and try to reclaim the folio.
|
||
*/
|
||
if (!folio_trylock(folio))
|
||
goto keep;
|
||
if (folio_test_dirty(folio) ||
|
||
folio_test_writeback(folio))
|
||
goto keep_locked;
|
||
mapping = folio_mapping(folio);
|
||
fallthrough;
|
||
case PAGE_CLEAN:
|
||
; /* try to free the folio below */
|
||
}
|
||
}
|
||
|
||
/*
|
||
* If the folio has buffers, try to free the buffer
|
||
* mappings associated with this folio. If we succeed
|
||
* we try to free the folio as well.
|
||
*
|
||
* We do this even if the folio is dirty.
|
||
* filemap_release_folio() does not perform I/O, but it
|
||
* is possible for a folio to have the dirty flag set,
|
||
* but it is actually clean (all its buffers are clean).
|
||
* This happens if the buffers were written out directly,
|
||
* with submit_bh(). ext3 will do this, as well as
|
||
* the blockdev mapping. filemap_release_folio() will
|
||
* discover that cleanness and will drop the buffers
|
||
* and mark the folio clean - it can be freed.
|
||
*
|
||
* Rarely, folios can have buffers and no ->mapping.
|
||
* These are the folios which were not successfully
|
||
* invalidated in truncate_cleanup_folio(). We try to
|
||
* drop those buffers here and if that worked, and the
|
||
* folio is no longer mapped into process address space
|
||
* (refcount == 1) it can be freed. Otherwise, leave
|
||
* the folio on the LRU so it is swappable.
|
||
*/
|
||
if (folio_needs_release(folio)) {
|
||
if (!filemap_release_folio(folio, sc->gfp_mask))
|
||
goto activate_locked;
|
||
if (!mapping && folio_ref_count(folio) == 1) {
|
||
folio_unlock(folio);
|
||
if (folio_put_testzero(folio))
|
||
goto free_it;
|
||
else {
|
||
/*
|
||
* rare race with speculative reference.
|
||
* the speculative reference will free
|
||
* this folio shortly, so we may
|
||
* increment nr_reclaimed here (and
|
||
* leave it off the LRU).
|
||
*/
|
||
nr_reclaimed += nr_pages;
|
||
continue;
|
||
}
|
||
}
|
||
}
|
||
|
||
if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) {
|
||
/* follow __remove_mapping for reference */
|
||
if (!folio_ref_freeze(folio, 1))
|
||
goto keep_locked;
|
||
/*
|
||
* The folio has only one reference left, which is
|
||
* from the isolation. After the caller puts the
|
||
* folio back on the lru and drops the reference, the
|
||
* folio will be freed anyway. It doesn't matter
|
||
* which lru it goes on. So we don't bother checking
|
||
* the dirty flag here.
|
||
*/
|
||
count_vm_events(PGLAZYFREED, nr_pages);
|
||
count_memcg_folio_events(folio, PGLAZYFREED, nr_pages);
|
||
} else if (!mapping || !__remove_mapping(mapping, folio, true,
|
||
sc->target_mem_cgroup))
|
||
goto keep_locked;
|
||
|
||
folio_unlock(folio);
|
||
free_it:
|
||
/*
|
||
* Folio may get swapped out as a whole, need to account
|
||
* all pages in it.
|
||
*/
|
||
nr_reclaimed += nr_pages;
|
||
|
||
/*
|
||
* Is there need to periodically free_folio_list? It would
|
||
* appear not as the counts should be low
|
||
*/
|
||
if (unlikely(folio_test_large(folio)))
|
||
destroy_large_folio(folio);
|
||
else
|
||
list_add(&folio->lru, &free_folios);
|
||
continue;
|
||
|
||
activate_locked_split:
|
||
/*
|
||
* The tail pages that are failed to add into swap cache
|
||
* reach here. Fixup nr_scanned and nr_pages.
|
||
*/
|
||
if (nr_pages > 1) {
|
||
sc->nr_scanned -= (nr_pages - 1);
|
||
nr_pages = 1;
|
||
}
|
||
activate_locked:
|
||
/* Not a candidate for swapping, so reclaim swap space. */
|
||
if (folio_test_swapcache(folio) &&
|
||
(mem_cgroup_swap_full(folio) || folio_test_mlocked(folio)))
|
||
folio_free_swap(folio);
|
||
VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
|
||
if (!folio_test_mlocked(folio)) {
|
||
int type = folio_is_file_lru(folio);
|
||
folio_set_active(folio);
|
||
stat->nr_activate[type] += nr_pages;
|
||
count_memcg_folio_events(folio, PGACTIVATE, nr_pages);
|
||
}
|
||
keep_locked:
|
||
folio_unlock(folio);
|
||
keep:
|
||
list_add(&folio->lru, &ret_folios);
|
||
VM_BUG_ON_FOLIO(folio_test_lru(folio) ||
|
||
folio_test_unevictable(folio), folio);
|
||
}
|
||
/* 'folio_list' is always empty here */
|
||
|
||
/* Migrate folios selected for demotion */
|
||
nr_reclaimed += demote_folio_list(&demote_folios, pgdat);
|
||
/* Folios that could not be demoted are still in @demote_folios */
|
||
if (!list_empty(&demote_folios)) {
|
||
/* Folios which weren't demoted go back on @folio_list */
|
||
list_splice_init(&demote_folios, folio_list);
|
||
|
||
/*
|
||
* goto retry to reclaim the undemoted folios in folio_list if
|
||
* desired.
|
||
*
|
||
* Reclaiming directly from top tier nodes is not often desired
|
||
* due to it breaking the LRU ordering: in general memory
|
||
* should be reclaimed from lower tier nodes and demoted from
|
||
* top tier nodes.
|
||
*
|
||
* However, disabling reclaim from top tier nodes entirely
|
||
* would cause ooms in edge scenarios where lower tier memory
|
||
* is unreclaimable for whatever reason, eg memory being
|
||
* mlocked or too hot to reclaim. We can disable reclaim
|
||
* from top tier nodes in proactive reclaim though as that is
|
||
* not real memory pressure.
|
||
*/
|
||
if (!sc->proactive) {
|
||
do_demote_pass = false;
|
||
goto retry;
|
||
}
|
||
}
|
||
|
||
pgactivate = stat->nr_activate[0] + stat->nr_activate[1];
|
||
|
||
mem_cgroup_uncharge_list(&free_folios);
|
||
try_to_unmap_flush();
|
||
free_unref_page_list(&free_folios);
|
||
|
||
list_splice(&ret_folios, folio_list);
|
||
count_vm_events(PGACTIVATE, pgactivate);
|
||
|
||
if (plug)
|
||
swap_write_unplug(plug);
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
unsigned int reclaim_clean_pages_from_list(struct zone *zone,
|
||
struct list_head *folio_list)
|
||
{
|
||
struct scan_control sc = {
|
||
.gfp_mask = GFP_KERNEL,
|
||
.may_unmap = 1,
|
||
};
|
||
struct reclaim_stat stat;
|
||
unsigned int nr_reclaimed;
|
||
struct folio *folio, *next;
|
||
LIST_HEAD(clean_folios);
|
||
unsigned int noreclaim_flag;
|
||
|
||
list_for_each_entry_safe(folio, next, folio_list, lru) {
|
||
if (!folio_test_hugetlb(folio) && folio_is_file_lru(folio) &&
|
||
!folio_test_dirty(folio) && !__folio_test_movable(folio) &&
|
||
!folio_test_unevictable(folio)) {
|
||
folio_clear_active(folio);
|
||
list_move(&folio->lru, &clean_folios);
|
||
}
|
||
}
|
||
|
||
/*
|
||
* We should be safe here since we are only dealing with file pages and
|
||
* we are not kswapd and therefore cannot write dirty file pages. But
|
||
* call memalloc_noreclaim_save() anyway, just in case these conditions
|
||
* change in the future.
|
||
*/
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
nr_reclaimed = shrink_folio_list(&clean_folios, zone->zone_pgdat, &sc,
|
||
&stat, true);
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
|
||
list_splice(&clean_folios, folio_list);
|
||
mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE,
|
||
-(long)nr_reclaimed);
|
||
/*
|
||
* Since lazyfree pages are isolated from file LRU from the beginning,
|
||
* they will rotate back to anonymous LRU in the end if it failed to
|
||
* discard so isolated count will be mismatched.
|
||
* Compensate the isolated count for both LRU lists.
|
||
*/
|
||
mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON,
|
||
stat.nr_lazyfree_fail);
|
||
mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE,
|
||
-(long)stat.nr_lazyfree_fail);
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
/*
|
||
* Update LRU sizes after isolating pages. The LRU size updates must
|
||
* be complete before mem_cgroup_update_lru_size due to a sanity check.
|
||
*/
|
||
static __always_inline void update_lru_sizes(struct lruvec *lruvec,
|
||
enum lru_list lru, unsigned long *nr_zone_taken)
|
||
{
|
||
int zid;
|
||
|
||
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
|
||
if (!nr_zone_taken[zid])
|
||
continue;
|
||
|
||
update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]);
|
||
}
|
||
|
||
}
|
||
|
||
#ifdef CONFIG_CMA
|
||
/*
|
||
* It is waste of effort to scan and reclaim CMA pages if it is not available
|
||
* for current allocation context. Kswapd can not be enrolled as it can not
|
||
* distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
|
||
*/
|
||
static bool skip_cma(struct folio *folio, struct scan_control *sc)
|
||
{
|
||
return !current_is_kswapd() &&
|
||
gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
|
||
folio_migratetype(folio) == MIGRATE_CMA;
|
||
}
|
||
#else
|
||
static bool skip_cma(struct folio *folio, struct scan_control *sc)
|
||
{
|
||
return false;
|
||
}
|
||
#endif
|
||
|
||
/*
|
||
* Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
|
||
*
|
||
* lruvec->lru_lock is heavily contended. Some of the functions that
|
||
* shrink the lists perform better by taking out a batch of pages
|
||
* and working on them outside the LRU lock.
|
||
*
|
||
* For pagecache intensive workloads, this function is the hottest
|
||
* spot in the kernel (apart from copy_*_user functions).
|
||
*
|
||
* Lru_lock must be held before calling this function.
|
||
*
|
||
* @nr_to_scan: The number of eligible pages to look through on the list.
|
||
* @lruvec: The LRU vector to pull pages from.
|
||
* @dst: The temp list to put pages on to.
|
||
* @nr_scanned: The number of pages that were scanned.
|
||
* @sc: The scan_control struct for this reclaim session
|
||
* @lru: LRU list id for isolating
|
||
*
|
||
* returns how many pages were moved onto *@dst.
|
||
*/
|
||
static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
|
||
struct lruvec *lruvec, struct list_head *dst,
|
||
unsigned long *nr_scanned, struct scan_control *sc,
|
||
enum lru_list lru)
|
||
{
|
||
struct list_head *src = &lruvec->lists[lru];
|
||
unsigned long nr_taken = 0;
|
||
unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
|
||
unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
|
||
unsigned long skipped = 0;
|
||
unsigned long scan, total_scan, nr_pages;
|
||
LIST_HEAD(folios_skipped);
|
||
|
||
total_scan = 0;
|
||
scan = 0;
|
||
while (scan < nr_to_scan && !list_empty(src)) {
|
||
struct list_head *move_to = src;
|
||
struct folio *folio;
|
||
|
||
folio = lru_to_folio(src);
|
||
prefetchw_prev_lru_folio(folio, src, flags);
|
||
|
||
nr_pages = folio_nr_pages(folio);
|
||
total_scan += nr_pages;
|
||
|
||
if (folio_zonenum(folio) > sc->reclaim_idx ||
|
||
skip_cma(folio, sc)) {
|
||
nr_skipped[folio_zonenum(folio)] += nr_pages;
|
||
move_to = &folios_skipped;
|
||
goto move;
|
||
}
|
||
|
||
/*
|
||
* Do not count skipped folios because that makes the function
|
||
* return with no isolated folios if the LRU mostly contains
|
||
* ineligible folios. This causes the VM to not reclaim any
|
||
* folios, triggering a premature OOM.
|
||
* Account all pages in a folio.
|
||
*/
|
||
scan += nr_pages;
|
||
|
||
if (!folio_test_lru(folio))
|
||
goto move;
|
||
if (!sc->may_unmap && folio_mapped(folio))
|
||
goto move;
|
||
|
||
/*
|
||
* Be careful not to clear the lru flag until after we're
|
||
* sure the folio is not being freed elsewhere -- the
|
||
* folio release code relies on it.
|
||
*/
|
||
if (unlikely(!folio_try_get(folio)))
|
||
goto move;
|
||
|
||
if (!folio_test_clear_lru(folio)) {
|
||
/* Another thread is already isolating this folio */
|
||
folio_put(folio);
|
||
goto move;
|
||
}
|
||
|
||
nr_taken += nr_pages;
|
||
nr_zone_taken[folio_zonenum(folio)] += nr_pages;
|
||
move_to = dst;
|
||
move:
|
||
list_move(&folio->lru, move_to);
|
||
}
|
||
|
||
/*
|
||
* Splice any skipped folios to the start of the LRU list. Note that
|
||
* this disrupts the LRU order when reclaiming for lower zones but
|
||
* we cannot splice to the tail. If we did then the SWAP_CLUSTER_MAX
|
||
* scanning would soon rescan the same folios to skip and waste lots
|
||
* of cpu cycles.
|
||
*/
|
||
if (!list_empty(&folios_skipped)) {
|
||
int zid;
|
||
|
||
list_splice(&folios_skipped, src);
|
||
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
|
||
if (!nr_skipped[zid])
|
||
continue;
|
||
|
||
__count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
|
||
skipped += nr_skipped[zid];
|
||
}
|
||
}
|
||
*nr_scanned = total_scan;
|
||
trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan,
|
||
total_scan, skipped, nr_taken, lru);
|
||
update_lru_sizes(lruvec, lru, nr_zone_taken);
|
||
return nr_taken;
|
||
}
|
||
|
||
/**
|
||
* folio_isolate_lru() - Try to isolate a folio from its LRU list.
|
||
* @folio: Folio to isolate from its LRU list.
|
||
*
|
||
* Isolate a @folio from an LRU list and adjust the vmstat statistic
|
||
* corresponding to whatever LRU list the folio was on.
|
||
*
|
||
* The folio will have its LRU flag cleared. If it was found on the
|
||
* active list, it will have the Active flag set. If it was found on the
|
||
* unevictable list, it will have the Unevictable flag set. These flags
|
||
* may need to be cleared by the caller before letting the page go.
|
||
*
|
||
* Context:
|
||
*
|
||
* (1) Must be called with an elevated refcount on the folio. This is a
|
||
* fundamental difference from isolate_lru_folios() (which is called
|
||
* without a stable reference).
|
||
* (2) The lru_lock must not be held.
|
||
* (3) Interrupts must be enabled.
|
||
*
|
||
* Return: true if the folio was removed from an LRU list.
|
||
* false if the folio was not on an LRU list.
|
||
*/
|
||
bool folio_isolate_lru(struct folio *folio)
|
||
{
|
||
bool ret = false;
|
||
|
||
VM_BUG_ON_FOLIO(!folio_ref_count(folio), folio);
|
||
|
||
if (folio_test_clear_lru(folio)) {
|
||
struct lruvec *lruvec;
|
||
|
||
folio_get(folio);
|
||
lruvec = folio_lruvec_lock_irq(folio);
|
||
lruvec_del_folio(lruvec, folio);
|
||
unlock_page_lruvec_irq(lruvec);
|
||
ret = true;
|
||
}
|
||
|
||
return ret;
|
||
}
|
||
|
||
/*
|
||
* A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and
|
||
* then get rescheduled. When there are massive number of tasks doing page
|
||
* allocation, such sleeping direct reclaimers may keep piling up on each CPU,
|
||
* the LRU list will go small and be scanned faster than necessary, leading to
|
||
* unnecessary swapping, thrashing and OOM.
|
||
*/
|
||
static int too_many_isolated(struct pglist_data *pgdat, int file,
|
||
struct scan_control *sc)
|
||
{
|
||
unsigned long inactive, isolated;
|
||
bool too_many;
|
||
|
||
if (current_is_kswapd())
|
||
return 0;
|
||
|
||
if (!writeback_throttling_sane(sc))
|
||
return 0;
|
||
|
||
if (file) {
|
||
inactive = node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
isolated = node_page_state(pgdat, NR_ISOLATED_FILE);
|
||
} else {
|
||
inactive = node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
isolated = node_page_state(pgdat, NR_ISOLATED_ANON);
|
||
}
|
||
|
||
/*
|
||
* GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they
|
||
* won't get blocked by normal direct-reclaimers, forming a circular
|
||
* deadlock.
|
||
*/
|
||
if (gfp_has_io_fs(sc->gfp_mask))
|
||
inactive >>= 3;
|
||
|
||
too_many = isolated > inactive;
|
||
|
||
/* Wake up tasks throttled due to too_many_isolated. */
|
||
if (!too_many)
|
||
wake_throttle_isolated(pgdat);
|
||
|
||
return too_many;
|
||
}
|
||
|
||
/*
|
||
* move_folios_to_lru() moves folios from private @list to appropriate LRU list.
|
||
* On return, @list is reused as a list of folios to be freed by the caller.
|
||
*
|
||
* Returns the number of pages moved to the given lruvec.
|
||
*/
|
||
static unsigned int move_folios_to_lru(struct lruvec *lruvec,
|
||
struct list_head *list)
|
||
{
|
||
int nr_pages, nr_moved = 0;
|
||
LIST_HEAD(folios_to_free);
|
||
|
||
while (!list_empty(list)) {
|
||
struct folio *folio = lru_to_folio(list);
|
||
|
||
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
|
||
list_del(&folio->lru);
|
||
if (unlikely(!folio_evictable(folio))) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
folio_putback_lru(folio);
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* The folio_set_lru needs to be kept here for list integrity.
|
||
* Otherwise:
|
||
* #0 move_folios_to_lru #1 release_pages
|
||
* if (!folio_put_testzero())
|
||
* if (folio_put_testzero())
|
||
* !lru //skip lru_lock
|
||
* folio_set_lru()
|
||
* list_add(&folio->lru,)
|
||
* list_add(&folio->lru,)
|
||
*/
|
||
folio_set_lru(folio);
|
||
|
||
if (unlikely(folio_put_testzero(folio))) {
|
||
__folio_clear_lru_flags(folio);
|
||
|
||
if (unlikely(folio_test_large(folio))) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
destroy_large_folio(folio);
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
} else
|
||
list_add(&folio->lru, &folios_to_free);
|
||
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* All pages were isolated from the same lruvec (and isolation
|
||
* inhibits memcg migration).
|
||
*/
|
||
VM_BUG_ON_FOLIO(!folio_matches_lruvec(folio, lruvec), folio);
|
||
lruvec_add_folio(lruvec, folio);
|
||
nr_pages = folio_nr_pages(folio);
|
||
nr_moved += nr_pages;
|
||
if (folio_test_active(folio))
|
||
workingset_age_nonresident(lruvec, nr_pages);
|
||
}
|
||
|
||
/*
|
||
* To save our caller's stack, now use input list for pages to free.
|
||
*/
|
||
list_splice(&folios_to_free, list);
|
||
|
||
return nr_moved;
|
||
}
|
||
|
||
/*
|
||
* If a kernel thread (such as nfsd for loop-back mounts) services a backing
|
||
* device by writing to the page cache it sets PF_LOCAL_THROTTLE. In this case
|
||
* we should not throttle. Otherwise it is safe to do so.
|
||
*/
|
||
static int current_may_throttle(void)
|
||
{
|
||
return !(current->flags & PF_LOCAL_THROTTLE);
|
||
}
|
||
|
||
/*
|
||
* shrink_inactive_list() is a helper for shrink_node(). It returns the number
|
||
* of reclaimed pages
|
||
*/
|
||
static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
|
||
struct lruvec *lruvec, struct scan_control *sc,
|
||
enum lru_list lru)
|
||
{
|
||
LIST_HEAD(folio_list);
|
||
unsigned long nr_scanned;
|
||
unsigned int nr_reclaimed = 0;
|
||
unsigned long nr_taken;
|
||
struct reclaim_stat stat;
|
||
bool file = is_file_lru(lru);
|
||
enum vm_event_item item;
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
bool stalled = false;
|
||
|
||
while (unlikely(too_many_isolated(pgdat, file, sc))) {
|
||
if (stalled)
|
||
return 0;
|
||
|
||
/* wait a bit for the reclaimer. */
|
||
stalled = true;
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);
|
||
|
||
/* We are about to die and free our memory. Return now. */
|
||
if (fatal_signal_pending(current))
|
||
return SWAP_CLUSTER_MAX;
|
||
}
|
||
|
||
lru_add_drain();
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &folio_list,
|
||
&nr_scanned, sc, lru);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
|
||
item = PGSCAN_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(item, nr_scanned);
|
||
__count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
|
||
__count_vm_events(PGSCAN_ANON + file, nr_scanned);
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
if (nr_taken == 0)
|
||
return 0;
|
||
|
||
nr_reclaimed = shrink_folio_list(&folio_list, pgdat, sc, &stat, false);
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
move_folios_to_lru(lruvec, &folio_list);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
|
||
item = PGSTEAL_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(item, nr_reclaimed);
|
||
__count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
|
||
__count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
lru_note_cost(lruvec, file, stat.nr_pageout, nr_scanned - nr_reclaimed);
|
||
mem_cgroup_uncharge_list(&folio_list);
|
||
free_unref_page_list(&folio_list);
|
||
|
||
/*
|
||
* If dirty folios are scanned that are not queued for IO, it
|
||
* implies that flushers are not doing their job. This can
|
||
* happen when memory pressure pushes dirty folios to the end of
|
||
* the LRU before the dirty limits are breached and the dirty
|
||
* data has expired. It can also happen when the proportion of
|
||
* dirty folios grows not through writes but through memory
|
||
* pressure reclaiming all the clean cache. And in some cases,
|
||
* the flushers simply cannot keep up with the allocation
|
||
* rate. Nudge the flusher threads in case they are asleep.
|
||
*/
|
||
if (stat.nr_unqueued_dirty == nr_taken) {
|
||
wakeup_flusher_threads(WB_REASON_VMSCAN);
|
||
/*
|
||
* For cgroupv1 dirty throttling is achieved by waking up
|
||
* the kernel flusher here and later waiting on folios
|
||
* which are in writeback to finish (see shrink_folio_list()).
|
||
*
|
||
* Flusher may not be able to issue writeback quickly
|
||
* enough for cgroupv1 writeback throttling to work
|
||
* on a large system.
|
||
*/
|
||
if (!writeback_throttling_sane(sc))
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK);
|
||
}
|
||
|
||
sc->nr.dirty += stat.nr_dirty;
|
||
sc->nr.congested += stat.nr_congested;
|
||
sc->nr.unqueued_dirty += stat.nr_unqueued_dirty;
|
||
sc->nr.writeback += stat.nr_writeback;
|
||
sc->nr.immediate += stat.nr_immediate;
|
||
sc->nr.taken += nr_taken;
|
||
if (file)
|
||
sc->nr.file_taken += nr_taken;
|
||
|
||
trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id,
|
||
nr_scanned, nr_reclaimed, &stat, sc->priority, file);
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
/*
|
||
* shrink_active_list() moves folios from the active LRU to the inactive LRU.
|
||
*
|
||
* We move them the other way if the folio is referenced by one or more
|
||
* processes.
|
||
*
|
||
* If the folios are mostly unmapped, the processing is fast and it is
|
||
* appropriate to hold lru_lock across the whole operation. But if
|
||
* the folios are mapped, the processing is slow (folio_referenced()), so
|
||
* we should drop lru_lock around each folio. It's impossible to balance
|
||
* this, so instead we remove the folios from the LRU while processing them.
|
||
* It is safe to rely on the active flag against the non-LRU folios in here
|
||
* because nobody will play with that bit on a non-LRU folio.
|
||
*
|
||
* The downside is that we have to touch folio->_refcount against each folio.
|
||
* But we had to alter folio->flags anyway.
|
||
*/
|
||
static void shrink_active_list(unsigned long nr_to_scan,
|
||
struct lruvec *lruvec,
|
||
struct scan_control *sc,
|
||
enum lru_list lru)
|
||
{
|
||
unsigned long nr_taken;
|
||
unsigned long nr_scanned;
|
||
unsigned long vm_flags;
|
||
LIST_HEAD(l_hold); /* The folios which were snipped off */
|
||
LIST_HEAD(l_active);
|
||
LIST_HEAD(l_inactive);
|
||
unsigned nr_deactivate, nr_activate;
|
||
unsigned nr_rotated = 0;
|
||
int file = is_file_lru(lru);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
lru_add_drain();
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
nr_taken = isolate_lru_folios(nr_to_scan, lruvec, &l_hold,
|
||
&nr_scanned, sc, lru);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);
|
||
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(PGREFILL, nr_scanned);
|
||
__count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
while (!list_empty(&l_hold)) {
|
||
struct folio *folio;
|
||
|
||
cond_resched();
|
||
folio = lru_to_folio(&l_hold);
|
||
list_del(&folio->lru);
|
||
|
||
if (unlikely(!folio_evictable(folio))) {
|
||
folio_putback_lru(folio);
|
||
continue;
|
||
}
|
||
|
||
if (unlikely(buffer_heads_over_limit)) {
|
||
if (folio_needs_release(folio) &&
|
||
folio_trylock(folio)) {
|
||
filemap_release_folio(folio, 0);
|
||
folio_unlock(folio);
|
||
}
|
||
}
|
||
|
||
/* Referenced or rmap lock contention: rotate */
|
||
if (folio_referenced(folio, 0, sc->target_mem_cgroup,
|
||
&vm_flags) != 0) {
|
||
/*
|
||
* Identify referenced, file-backed active folios and
|
||
* give them one more trip around the active list. So
|
||
* that executable code get better chances to stay in
|
||
* memory under moderate memory pressure. Anon folios
|
||
* are not likely to be evicted by use-once streaming
|
||
* IO, plus JVM can create lots of anon VM_EXEC folios,
|
||
* so we ignore them here.
|
||
*/
|
||
if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio)) {
|
||
nr_rotated += folio_nr_pages(folio);
|
||
list_add(&folio->lru, &l_active);
|
||
continue;
|
||
}
|
||
}
|
||
|
||
folio_clear_active(folio); /* we are de-activating */
|
||
folio_set_workingset(folio);
|
||
list_add(&folio->lru, &l_inactive);
|
||
}
|
||
|
||
/*
|
||
* Move folios back to the lru list.
|
||
*/
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
nr_activate = move_folios_to_lru(lruvec, &l_active);
|
||
nr_deactivate = move_folios_to_lru(lruvec, &l_inactive);
|
||
/* Keep all free folios in l_active list */
|
||
list_splice(&l_inactive, &l_active);
|
||
|
||
__count_vm_events(PGDEACTIVATE, nr_deactivate);
|
||
__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
|
||
|
||
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
if (nr_rotated)
|
||
lru_note_cost(lruvec, file, 0, nr_rotated);
|
||
mem_cgroup_uncharge_list(&l_active);
|
||
free_unref_page_list(&l_active);
|
||
trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
|
||
nr_deactivate, nr_rotated, sc->priority, file);
|
||
}
|
||
|
||
static unsigned int reclaim_folio_list(struct list_head *folio_list,
|
||
struct pglist_data *pgdat)
|
||
{
|
||
struct reclaim_stat dummy_stat;
|
||
unsigned int nr_reclaimed;
|
||
struct folio *folio;
|
||
struct scan_control sc = {
|
||
.gfp_mask = GFP_KERNEL,
|
||
.may_writepage = 1,
|
||
.may_unmap = 1,
|
||
.may_swap = 1,
|
||
.no_demotion = 1,
|
||
};
|
||
|
||
nr_reclaimed = shrink_folio_list(folio_list, pgdat, &sc, &dummy_stat, false);
|
||
while (!list_empty(folio_list)) {
|
||
folio = lru_to_folio(folio_list);
|
||
list_del(&folio->lru);
|
||
folio_putback_lru(folio);
|
||
}
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
unsigned long reclaim_pages(struct list_head *folio_list)
|
||
{
|
||
int nid;
|
||
unsigned int nr_reclaimed = 0;
|
||
LIST_HEAD(node_folio_list);
|
||
unsigned int noreclaim_flag;
|
||
|
||
if (list_empty(folio_list))
|
||
return nr_reclaimed;
|
||
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
|
||
nid = folio_nid(lru_to_folio(folio_list));
|
||
do {
|
||
struct folio *folio = lru_to_folio(folio_list);
|
||
|
||
if (nid == folio_nid(folio)) {
|
||
folio_clear_active(folio);
|
||
list_move(&folio->lru, &node_folio_list);
|
||
continue;
|
||
}
|
||
|
||
nr_reclaimed += reclaim_folio_list(&node_folio_list, NODE_DATA(nid));
|
||
nid = folio_nid(lru_to_folio(folio_list));
|
||
} while (!list_empty(folio_list));
|
||
|
||
nr_reclaimed += reclaim_folio_list(&node_folio_list, NODE_DATA(nid));
|
||
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
|
||
struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
if (is_active_lru(lru)) {
|
||
if (sc->may_deactivate & (1 << is_file_lru(lru)))
|
||
shrink_active_list(nr_to_scan, lruvec, sc, lru);
|
||
else
|
||
sc->skipped_deactivate = 1;
|
||
return 0;
|
||
}
|
||
|
||
return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);
|
||
}
|
||
|
||
/*
|
||
* The inactive anon list should be small enough that the VM never has
|
||
* to do too much work.
|
||
*
|
||
* The inactive file list should be small enough to leave most memory
|
||
* to the established workingset on the scan-resistant active list,
|
||
* but large enough to avoid thrashing the aggregate readahead window.
|
||
*
|
||
* Both inactive lists should also be large enough that each inactive
|
||
* folio has a chance to be referenced again before it is reclaimed.
|
||
*
|
||
* If that fails and refaulting is observed, the inactive list grows.
|
||
*
|
||
* The inactive_ratio is the target ratio of ACTIVE to INACTIVE folios
|
||
* on this LRU, maintained by the pageout code. An inactive_ratio
|
||
* of 3 means 3:1 or 25% of the folios are kept on the inactive list.
|
||
*
|
||
* total target max
|
||
* memory ratio inactive
|
||
* -------------------------------------
|
||
* 10MB 1 5MB
|
||
* 100MB 1 50MB
|
||
* 1GB 3 250MB
|
||
* 10GB 10 0.9GB
|
||
* 100GB 31 3GB
|
||
* 1TB 101 10GB
|
||
* 10TB 320 32GB
|
||
*/
|
||
static bool inactive_is_low(struct lruvec *lruvec, enum lru_list inactive_lru)
|
||
{
|
||
enum lru_list active_lru = inactive_lru + LRU_ACTIVE;
|
||
unsigned long inactive, active;
|
||
unsigned long inactive_ratio;
|
||
unsigned long gb;
|
||
|
||
inactive = lruvec_page_state(lruvec, NR_LRU_BASE + inactive_lru);
|
||
active = lruvec_page_state(lruvec, NR_LRU_BASE + active_lru);
|
||
|
||
gb = (inactive + active) >> (30 - PAGE_SHIFT);
|
||
if (gb)
|
||
inactive_ratio = int_sqrt(10 * gb);
|
||
else
|
||
inactive_ratio = 1;
|
||
|
||
return inactive * inactive_ratio < active;
|
||
}
|
||
|
||
enum scan_balance {
|
||
SCAN_EQUAL,
|
||
SCAN_FRACT,
|
||
SCAN_ANON,
|
||
SCAN_FILE,
|
||
};
|
||
|
||
static void prepare_scan_control(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
unsigned long file;
|
||
struct lruvec *target_lruvec;
|
||
|
||
if (lru_gen_enabled())
|
||
return;
|
||
|
||
target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
|
||
|
||
/*
|
||
* Flush the memory cgroup stats, so that we read accurate per-memcg
|
||
* lruvec stats for heuristics.
|
||
*/
|
||
mem_cgroup_flush_stats(sc->target_mem_cgroup);
|
||
|
||
/*
|
||
* Determine the scan balance between anon and file LRUs.
|
||
*/
|
||
spin_lock_irq(&target_lruvec->lru_lock);
|
||
sc->anon_cost = target_lruvec->anon_cost;
|
||
sc->file_cost = target_lruvec->file_cost;
|
||
spin_unlock_irq(&target_lruvec->lru_lock);
|
||
|
||
/*
|
||
* Target desirable inactive:active list ratios for the anon
|
||
* and file LRU lists.
|
||
*/
|
||
if (!sc->force_deactivate) {
|
||
unsigned long refaults;
|
||
|
||
/*
|
||
* When refaults are being observed, it means a new
|
||
* workingset is being established. Deactivate to get
|
||
* rid of any stale active pages quickly.
|
||
*/
|
||
refaults = lruvec_page_state(target_lruvec,
|
||
WORKINGSET_ACTIVATE_ANON);
|
||
if (refaults != target_lruvec->refaults[WORKINGSET_ANON] ||
|
||
inactive_is_low(target_lruvec, LRU_INACTIVE_ANON))
|
||
sc->may_deactivate |= DEACTIVATE_ANON;
|
||
else
|
||
sc->may_deactivate &= ~DEACTIVATE_ANON;
|
||
|
||
refaults = lruvec_page_state(target_lruvec,
|
||
WORKINGSET_ACTIVATE_FILE);
|
||
if (refaults != target_lruvec->refaults[WORKINGSET_FILE] ||
|
||
inactive_is_low(target_lruvec, LRU_INACTIVE_FILE))
|
||
sc->may_deactivate |= DEACTIVATE_FILE;
|
||
else
|
||
sc->may_deactivate &= ~DEACTIVATE_FILE;
|
||
} else
|
||
sc->may_deactivate = DEACTIVATE_ANON | DEACTIVATE_FILE;
|
||
|
||
/*
|
||
* If we have plenty of inactive file pages that aren't
|
||
* thrashing, try to reclaim those first before touching
|
||
* anonymous pages.
|
||
*/
|
||
file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
|
||
if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE))
|
||
sc->cache_trim_mode = 1;
|
||
else
|
||
sc->cache_trim_mode = 0;
|
||
|
||
/*
|
||
* Prevent the reclaimer from falling into the cache trap: as
|
||
* cache pages start out inactive, every cache fault will tip
|
||
* the scan balance towards the file LRU. And as the file LRU
|
||
* shrinks, so does the window for rotation from references.
|
||
* This means we have a runaway feedback loop where a tiny
|
||
* thrashing file LRU becomes infinitely more attractive than
|
||
* anon pages. Try to detect this based on file LRU size.
|
||
*/
|
||
if (!cgroup_reclaim(sc)) {
|
||
unsigned long total_high_wmark = 0;
|
||
unsigned long free, anon;
|
||
int z;
|
||
|
||
free = sum_zone_node_page_state(pgdat->node_id, NR_FREE_PAGES);
|
||
file = node_page_state(pgdat, NR_ACTIVE_FILE) +
|
||
node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
|
||
for (z = 0; z < MAX_NR_ZONES; z++) {
|
||
struct zone *zone = &pgdat->node_zones[z];
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
total_high_wmark += high_wmark_pages(zone);
|
||
}
|
||
|
||
/*
|
||
* Consider anon: if that's low too, this isn't a
|
||
* runaway file reclaim problem, but rather just
|
||
* extreme pressure. Reclaim as per usual then.
|
||
*/
|
||
anon = node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
|
||
sc->file_is_tiny =
|
||
file + free <= total_high_wmark &&
|
||
!(sc->may_deactivate & DEACTIVATE_ANON) &&
|
||
anon >> sc->priority;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Determine how aggressively the anon and file LRU lists should be
|
||
* scanned.
|
||
*
|
||
* nr[0] = anon inactive folios to scan; nr[1] = anon active folios to scan
|
||
* nr[2] = file inactive folios to scan; nr[3] = file active folios to scan
|
||
*/
|
||
static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
|
||
unsigned long *nr)
|
||
{
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
unsigned long anon_cost, file_cost, total_cost;
|
||
int swappiness = mem_cgroup_swappiness(memcg);
|
||
u64 fraction[ANON_AND_FILE];
|
||
u64 denominator = 0; /* gcc */
|
||
enum scan_balance scan_balance;
|
||
unsigned long ap, fp;
|
||
enum lru_list lru;
|
||
|
||
/* If we have no swap space, do not bother scanning anon folios. */
|
||
if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) {
|
||
scan_balance = SCAN_FILE;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* Global reclaim will swap to prevent OOM even with no
|
||
* swappiness, but memcg users want to use this knob to
|
||
* disable swapping for individual groups completely when
|
||
* using the memory controller's swap limit feature would be
|
||
* too expensive.
|
||
*/
|
||
if (cgroup_reclaim(sc) && !swappiness) {
|
||
scan_balance = SCAN_FILE;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* Do not apply any pressure balancing cleverness when the
|
||
* system is close to OOM, scan both anon and file equally
|
||
* (unless the swappiness setting disagrees with swapping).
|
||
*/
|
||
if (!sc->priority && swappiness) {
|
||
scan_balance = SCAN_EQUAL;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* If the system is almost out of file pages, force-scan anon.
|
||
*/
|
||
if (sc->file_is_tiny) {
|
||
scan_balance = SCAN_ANON;
|
||
goto out;
|
||
}
|
||
|
||
/*
|
||
* If there is enough inactive page cache, we do not reclaim
|
||
* anything from the anonymous working right now.
|
||
*/
|
||
if (sc->cache_trim_mode) {
|
||
scan_balance = SCAN_FILE;
|
||
goto out;
|
||
}
|
||
|
||
scan_balance = SCAN_FRACT;
|
||
/*
|
||
* Calculate the pressure balance between anon and file pages.
|
||
*
|
||
* The amount of pressure we put on each LRU is inversely
|
||
* proportional to the cost of reclaiming each list, as
|
||
* determined by the share of pages that are refaulting, times
|
||
* the relative IO cost of bringing back a swapped out
|
||
* anonymous page vs reloading a filesystem page (swappiness).
|
||
*
|
||
* Although we limit that influence to ensure no list gets
|
||
* left behind completely: at least a third of the pressure is
|
||
* applied, before swappiness.
|
||
*
|
||
* With swappiness at 100, anon and file have equal IO cost.
|
||
*/
|
||
total_cost = sc->anon_cost + sc->file_cost;
|
||
anon_cost = total_cost + sc->anon_cost;
|
||
file_cost = total_cost + sc->file_cost;
|
||
total_cost = anon_cost + file_cost;
|
||
|
||
ap = swappiness * (total_cost + 1);
|
||
ap /= anon_cost + 1;
|
||
|
||
fp = (200 - swappiness) * (total_cost + 1);
|
||
fp /= file_cost + 1;
|
||
|
||
fraction[0] = ap;
|
||
fraction[1] = fp;
|
||
denominator = ap + fp;
|
||
out:
|
||
for_each_evictable_lru(lru) {
|
||
int file = is_file_lru(lru);
|
||
unsigned long lruvec_size;
|
||
unsigned long low, min;
|
||
unsigned long scan;
|
||
|
||
lruvec_size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
|
||
mem_cgroup_protection(sc->target_mem_cgroup, memcg,
|
||
&min, &low);
|
||
|
||
if (min || low) {
|
||
/*
|
||
* Scale a cgroup's reclaim pressure by proportioning
|
||
* its current usage to its memory.low or memory.min
|
||
* setting.
|
||
*
|
||
* This is important, as otherwise scanning aggression
|
||
* becomes extremely binary -- from nothing as we
|
||
* approach the memory protection threshold, to totally
|
||
* nominal as we exceed it. This results in requiring
|
||
* setting extremely liberal protection thresholds. It
|
||
* also means we simply get no protection at all if we
|
||
* set it too low, which is not ideal.
|
||
*
|
||
* If there is any protection in place, we reduce scan
|
||
* pressure by how much of the total memory used is
|
||
* within protection thresholds.
|
||
*
|
||
* There is one special case: in the first reclaim pass,
|
||
* we skip over all groups that are within their low
|
||
* protection. If that fails to reclaim enough pages to
|
||
* satisfy the reclaim goal, we come back and override
|
||
* the best-effort low protection. However, we still
|
||
* ideally want to honor how well-behaved groups are in
|
||
* that case instead of simply punishing them all
|
||
* equally. As such, we reclaim them based on how much
|
||
* memory they are using, reducing the scan pressure
|
||
* again by how much of the total memory used is under
|
||
* hard protection.
|
||
*/
|
||
unsigned long cgroup_size = mem_cgroup_size(memcg);
|
||
unsigned long protection;
|
||
|
||
/* memory.low scaling, make sure we retry before OOM */
|
||
if (!sc->memcg_low_reclaim && low > min) {
|
||
protection = low;
|
||
sc->memcg_low_skipped = 1;
|
||
} else {
|
||
protection = min;
|
||
}
|
||
|
||
/* Avoid TOCTOU with earlier protection check */
|
||
cgroup_size = max(cgroup_size, protection);
|
||
|
||
scan = lruvec_size - lruvec_size * protection /
|
||
(cgroup_size + 1);
|
||
|
||
/*
|
||
* Minimally target SWAP_CLUSTER_MAX pages to keep
|
||
* reclaim moving forwards, avoiding decrementing
|
||
* sc->priority further than desirable.
|
||
*/
|
||
scan = max(scan, SWAP_CLUSTER_MAX);
|
||
} else {
|
||
scan = lruvec_size;
|
||
}
|
||
|
||
scan >>= sc->priority;
|
||
|
||
/*
|
||
* If the cgroup's already been deleted, make sure to
|
||
* scrape out the remaining cache.
|
||
*/
|
||
if (!scan && !mem_cgroup_online(memcg))
|
||
scan = min(lruvec_size, SWAP_CLUSTER_MAX);
|
||
|
||
switch (scan_balance) {
|
||
case SCAN_EQUAL:
|
||
/* Scan lists relative to size */
|
||
break;
|
||
case SCAN_FRACT:
|
||
/*
|
||
* Scan types proportional to swappiness and
|
||
* their relative recent reclaim efficiency.
|
||
* Make sure we don't miss the last page on
|
||
* the offlined memory cgroups because of a
|
||
* round-off error.
|
||
*/
|
||
scan = mem_cgroup_online(memcg) ?
|
||
div64_u64(scan * fraction[file], denominator) :
|
||
DIV64_U64_ROUND_UP(scan * fraction[file],
|
||
denominator);
|
||
break;
|
||
case SCAN_FILE:
|
||
case SCAN_ANON:
|
||
/* Scan one type exclusively */
|
||
if ((scan_balance == SCAN_FILE) != file)
|
||
scan = 0;
|
||
break;
|
||
default:
|
||
/* Look ma, no brain */
|
||
BUG();
|
||
}
|
||
|
||
nr[lru] = scan;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Anonymous LRU management is a waste if there is
|
||
* ultimately no way to reclaim the memory.
|
||
*/
|
||
static bool can_age_anon_pages(struct pglist_data *pgdat,
|
||
struct scan_control *sc)
|
||
{
|
||
/* Aging the anon LRU is valuable if swap is present: */
|
||
if (total_swap_pages > 0)
|
||
return true;
|
||
|
||
/* Also valuable if anon pages can be demoted: */
|
||
return can_demote(pgdat->node_id, sc);
|
||
}
|
||
|
||
#ifdef CONFIG_LRU_GEN
|
||
|
||
#ifdef CONFIG_LRU_GEN_ENABLED
|
||
DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS);
|
||
#define get_cap(cap) static_branch_likely(&lru_gen_caps[cap])
|
||
#else
|
||
DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS);
|
||
#define get_cap(cap) static_branch_unlikely(&lru_gen_caps[cap])
|
||
#endif
|
||
|
||
static bool should_walk_mmu(void)
|
||
{
|
||
return arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK);
|
||
}
|
||
|
||
static bool should_clear_pmd_young(void)
|
||
{
|
||
return arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG);
|
||
}
|
||
|
||
/******************************************************************************
|
||
* shorthand helpers
|
||
******************************************************************************/
|
||
|
||
#define LRU_REFS_FLAGS (BIT(PG_referenced) | BIT(PG_workingset))
|
||
|
||
#define DEFINE_MAX_SEQ(lruvec) \
|
||
unsigned long max_seq = READ_ONCE((lruvec)->lrugen.max_seq)
|
||
|
||
#define DEFINE_MIN_SEQ(lruvec) \
|
||
unsigned long min_seq[ANON_AND_FILE] = { \
|
||
READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_ANON]), \
|
||
READ_ONCE((lruvec)->lrugen.min_seq[LRU_GEN_FILE]), \
|
||
}
|
||
|
||
#define for_each_gen_type_zone(gen, type, zone) \
|
||
for ((gen) = 0; (gen) < MAX_NR_GENS; (gen)++) \
|
||
for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \
|
||
for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++)
|
||
|
||
#define get_memcg_gen(seq) ((seq) % MEMCG_NR_GENS)
|
||
#define get_memcg_bin(bin) ((bin) % MEMCG_NR_BINS)
|
||
|
||
static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid)
|
||
{
|
||
struct pglist_data *pgdat = NODE_DATA(nid);
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
if (memcg) {
|
||
struct lruvec *lruvec = &memcg->nodeinfo[nid]->lruvec;
|
||
|
||
/* see the comment in mem_cgroup_lruvec() */
|
||
if (!lruvec->pgdat)
|
||
lruvec->pgdat = pgdat;
|
||
|
||
return lruvec;
|
||
}
|
||
#endif
|
||
VM_WARN_ON_ONCE(!mem_cgroup_disabled());
|
||
|
||
return &pgdat->__lruvec;
|
||
}
|
||
|
||
static int get_swappiness(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
if (!sc->may_swap)
|
||
return 0;
|
||
|
||
if (!can_demote(pgdat->node_id, sc) &&
|
||
mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH)
|
||
return 0;
|
||
|
||
return mem_cgroup_swappiness(memcg);
|
||
}
|
||
|
||
static int get_nr_gens(struct lruvec *lruvec, int type)
|
||
{
|
||
return lruvec->lrugen.max_seq - lruvec->lrugen.min_seq[type] + 1;
|
||
}
|
||
|
||
static bool __maybe_unused seq_is_valid(struct lruvec *lruvec)
|
||
{
|
||
/* see the comment on lru_gen_folio */
|
||
return get_nr_gens(lruvec, LRU_GEN_FILE) >= MIN_NR_GENS &&
|
||
get_nr_gens(lruvec, LRU_GEN_FILE) <= get_nr_gens(lruvec, LRU_GEN_ANON) &&
|
||
get_nr_gens(lruvec, LRU_GEN_ANON) <= MAX_NR_GENS;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* Bloom filters
|
||
******************************************************************************/
|
||
|
||
/*
|
||
* Bloom filters with m=1<<15, k=2 and the false positive rates of ~1/5 when
|
||
* n=10,000 and ~1/2 when n=20,000, where, conventionally, m is the number of
|
||
* bits in a bitmap, k is the number of hash functions and n is the number of
|
||
* inserted items.
|
||
*
|
||
* Page table walkers use one of the two filters to reduce their search space.
|
||
* To get rid of non-leaf entries that no longer have enough leaf entries, the
|
||
* aging uses the double-buffering technique to flip to the other filter each
|
||
* time it produces a new generation. For non-leaf entries that have enough
|
||
* leaf entries, the aging carries them over to the next generation in
|
||
* walk_pmd_range(); the eviction also report them when walking the rmap
|
||
* in lru_gen_look_around().
|
||
*
|
||
* For future optimizations:
|
||
* 1. It's not necessary to keep both filters all the time. The spare one can be
|
||
* freed after the RCU grace period and reallocated if needed again.
|
||
* 2. And when reallocating, it's worth scaling its size according to the number
|
||
* of inserted entries in the other filter, to reduce the memory overhead on
|
||
* small systems and false positives on large systems.
|
||
* 3. Jenkins' hash function is an alternative to Knuth's.
|
||
*/
|
||
#define BLOOM_FILTER_SHIFT 15
|
||
|
||
static inline int filter_gen_from_seq(unsigned long seq)
|
||
{
|
||
return seq % NR_BLOOM_FILTERS;
|
||
}
|
||
|
||
static void get_item_key(void *item, int *key)
|
||
{
|
||
u32 hash = hash_ptr(item, BLOOM_FILTER_SHIFT * 2);
|
||
|
||
BUILD_BUG_ON(BLOOM_FILTER_SHIFT * 2 > BITS_PER_TYPE(u32));
|
||
|
||
key[0] = hash & (BIT(BLOOM_FILTER_SHIFT) - 1);
|
||
key[1] = hash >> BLOOM_FILTER_SHIFT;
|
||
}
|
||
|
||
static bool test_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq,
|
||
void *item)
|
||
{
|
||
int key[2];
|
||
unsigned long *filter;
|
||
int gen = filter_gen_from_seq(seq);
|
||
|
||
filter = READ_ONCE(mm_state->filters[gen]);
|
||
if (!filter)
|
||
return true;
|
||
|
||
get_item_key(item, key);
|
||
|
||
return test_bit(key[0], filter) && test_bit(key[1], filter);
|
||
}
|
||
|
||
static void update_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq,
|
||
void *item)
|
||
{
|
||
int key[2];
|
||
unsigned long *filter;
|
||
int gen = filter_gen_from_seq(seq);
|
||
|
||
filter = READ_ONCE(mm_state->filters[gen]);
|
||
if (!filter)
|
||
return;
|
||
|
||
get_item_key(item, key);
|
||
|
||
if (!test_bit(key[0], filter))
|
||
set_bit(key[0], filter);
|
||
if (!test_bit(key[1], filter))
|
||
set_bit(key[1], filter);
|
||
}
|
||
|
||
static void reset_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq)
|
||
{
|
||
unsigned long *filter;
|
||
int gen = filter_gen_from_seq(seq);
|
||
|
||
filter = mm_state->filters[gen];
|
||
if (filter) {
|
||
bitmap_clear(filter, 0, BIT(BLOOM_FILTER_SHIFT));
|
||
return;
|
||
}
|
||
|
||
filter = bitmap_zalloc(BIT(BLOOM_FILTER_SHIFT),
|
||
__GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
||
WRITE_ONCE(mm_state->filters[gen], filter);
|
||
}
|
||
|
||
/******************************************************************************
|
||
* mm_struct list
|
||
******************************************************************************/
|
||
|
||
#ifdef CONFIG_LRU_GEN_WALKS_MMU
|
||
|
||
static struct lru_gen_mm_list *get_mm_list(struct mem_cgroup *memcg)
|
||
{
|
||
static struct lru_gen_mm_list mm_list = {
|
||
.fifo = LIST_HEAD_INIT(mm_list.fifo),
|
||
.lock = __SPIN_LOCK_UNLOCKED(mm_list.lock),
|
||
};
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
if (memcg)
|
||
return &memcg->mm_list;
|
||
#endif
|
||
VM_WARN_ON_ONCE(!mem_cgroup_disabled());
|
||
|
||
return &mm_list;
|
||
}
|
||
|
||
static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)
|
||
{
|
||
return &lruvec->mm_state;
|
||
}
|
||
|
||
static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
|
||
{
|
||
int key;
|
||
struct mm_struct *mm;
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(walk->lruvec);
|
||
|
||
mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list);
|
||
key = pgdat->node_id % BITS_PER_TYPE(mm->lru_gen.bitmap);
|
||
|
||
if (!walk->force_scan && !test_bit(key, &mm->lru_gen.bitmap))
|
||
return NULL;
|
||
|
||
clear_bit(key, &mm->lru_gen.bitmap);
|
||
|
||
return mmget_not_zero(mm) ? mm : NULL;
|
||
}
|
||
|
||
void lru_gen_add_mm(struct mm_struct *mm)
|
||
{
|
||
int nid;
|
||
struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm);
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
|
||
VM_WARN_ON_ONCE(!list_empty(&mm->lru_gen.list));
|
||
#ifdef CONFIG_MEMCG
|
||
VM_WARN_ON_ONCE(mm->lru_gen.memcg);
|
||
mm->lru_gen.memcg = memcg;
|
||
#endif
|
||
spin_lock(&mm_list->lock);
|
||
|
||
for_each_node_state(nid, N_MEMORY) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
/* the first addition since the last iteration */
|
||
if (mm_state->tail == &mm_list->fifo)
|
||
mm_state->tail = &mm->lru_gen.list;
|
||
}
|
||
|
||
list_add_tail(&mm->lru_gen.list, &mm_list->fifo);
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
}
|
||
|
||
void lru_gen_del_mm(struct mm_struct *mm)
|
||
{
|
||
int nid;
|
||
struct lru_gen_mm_list *mm_list;
|
||
struct mem_cgroup *memcg = NULL;
|
||
|
||
if (list_empty(&mm->lru_gen.list))
|
||
return;
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
memcg = mm->lru_gen.memcg;
|
||
#endif
|
||
mm_list = get_mm_list(memcg);
|
||
|
||
spin_lock(&mm_list->lock);
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
/* where the current iteration continues after */
|
||
if (mm_state->head == &mm->lru_gen.list)
|
||
mm_state->head = mm_state->head->prev;
|
||
|
||
/* where the last iteration ended before */
|
||
if (mm_state->tail == &mm->lru_gen.list)
|
||
mm_state->tail = mm_state->tail->next;
|
||
}
|
||
|
||
list_del_init(&mm->lru_gen.list);
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
mem_cgroup_put(mm->lru_gen.memcg);
|
||
mm->lru_gen.memcg = NULL;
|
||
#endif
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
void lru_gen_migrate_mm(struct mm_struct *mm)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
struct task_struct *task = rcu_dereference_protected(mm->owner, true);
|
||
|
||
VM_WARN_ON_ONCE(task->mm != mm);
|
||
lockdep_assert_held(&task->alloc_lock);
|
||
|
||
/* for mm_update_next_owner() */
|
||
if (mem_cgroup_disabled())
|
||
return;
|
||
|
||
/* migration can happen before addition */
|
||
if (!mm->lru_gen.memcg)
|
||
return;
|
||
|
||
rcu_read_lock();
|
||
memcg = mem_cgroup_from_task(task);
|
||
rcu_read_unlock();
|
||
if (memcg == mm->lru_gen.memcg)
|
||
return;
|
||
|
||
VM_WARN_ON_ONCE(list_empty(&mm->lru_gen.list));
|
||
|
||
lru_gen_del_mm(mm);
|
||
lru_gen_add_mm(mm);
|
||
}
|
||
#endif
|
||
|
||
#else /* !CONFIG_LRU_GEN_WALKS_MMU */
|
||
|
||
static struct lru_gen_mm_list *get_mm_list(struct mem_cgroup *memcg)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
|
||
{
|
||
return NULL;
|
||
}
|
||
|
||
#endif
|
||
|
||
static void reset_mm_stats(struct lruvec *lruvec, struct lru_gen_mm_walk *walk, bool last)
|
||
{
|
||
int i;
|
||
int hist;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
lockdep_assert_held(&get_mm_list(lruvec_memcg(lruvec))->lock);
|
||
|
||
if (walk) {
|
||
hist = lru_hist_from_seq(walk->max_seq);
|
||
|
||
for (i = 0; i < NR_MM_STATS; i++) {
|
||
WRITE_ONCE(mm_state->stats[hist][i],
|
||
mm_state->stats[hist][i] + walk->mm_stats[i]);
|
||
walk->mm_stats[i] = 0;
|
||
}
|
||
}
|
||
|
||
if (NR_HIST_GENS > 1 && last) {
|
||
hist = lru_hist_from_seq(mm_state->seq + 1);
|
||
|
||
for (i = 0; i < NR_MM_STATS; i++)
|
||
WRITE_ONCE(mm_state->stats[hist][i], 0);
|
||
}
|
||
}
|
||
|
||
static bool iterate_mm_list(struct lruvec *lruvec, struct lru_gen_mm_walk *walk,
|
||
struct mm_struct **iter)
|
||
{
|
||
bool first = false;
|
||
bool last = false;
|
||
struct mm_struct *mm = NULL;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
/*
|
||
* mm_state->seq is incremented after each iteration of mm_list. There
|
||
* are three interesting cases for this page table walker:
|
||
* 1. It tries to start a new iteration with a stale max_seq: there is
|
||
* nothing left to do.
|
||
* 2. It started the next iteration: it needs to reset the Bloom filter
|
||
* so that a fresh set of PTE tables can be recorded.
|
||
* 3. It ended the current iteration: it needs to reset the mm stats
|
||
* counters and tell its caller to increment max_seq.
|
||
*/
|
||
spin_lock(&mm_list->lock);
|
||
|
||
VM_WARN_ON_ONCE(mm_state->seq + 1 < walk->max_seq);
|
||
|
||
if (walk->max_seq <= mm_state->seq)
|
||
goto done;
|
||
|
||
if (!mm_state->head)
|
||
mm_state->head = &mm_list->fifo;
|
||
|
||
if (mm_state->head == &mm_list->fifo)
|
||
first = true;
|
||
|
||
do {
|
||
mm_state->head = mm_state->head->next;
|
||
if (mm_state->head == &mm_list->fifo) {
|
||
WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
|
||
last = true;
|
||
break;
|
||
}
|
||
|
||
/* force scan for those added after the last iteration */
|
||
if (!mm_state->tail || mm_state->tail == mm_state->head) {
|
||
mm_state->tail = mm_state->head->next;
|
||
walk->force_scan = true;
|
||
}
|
||
} while (!(mm = get_next_mm(walk)));
|
||
done:
|
||
if (*iter || last)
|
||
reset_mm_stats(lruvec, walk, last);
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
|
||
if (mm && first)
|
||
reset_bloom_filter(mm_state, walk->max_seq + 1);
|
||
|
||
if (*iter)
|
||
mmput_async(*iter);
|
||
|
||
*iter = mm;
|
||
|
||
return last;
|
||
}
|
||
|
||
static bool iterate_mm_list_nowalk(struct lruvec *lruvec, unsigned long max_seq)
|
||
{
|
||
bool success = false;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
spin_lock(&mm_list->lock);
|
||
|
||
VM_WARN_ON_ONCE(mm_state->seq + 1 < max_seq);
|
||
|
||
if (max_seq > mm_state->seq) {
|
||
mm_state->head = NULL;
|
||
mm_state->tail = NULL;
|
||
WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
|
||
reset_mm_stats(lruvec, NULL, true);
|
||
success = true;
|
||
}
|
||
|
||
spin_unlock(&mm_list->lock);
|
||
|
||
return success;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* PID controller
|
||
******************************************************************************/
|
||
|
||
/*
|
||
* A feedback loop based on Proportional-Integral-Derivative (PID) controller.
|
||
*
|
||
* The P term is refaulted/(evicted+protected) from a tier in the generation
|
||
* currently being evicted; the I term is the exponential moving average of the
|
||
* P term over the generations previously evicted, using the smoothing factor
|
||
* 1/2; the D term isn't supported.
|
||
*
|
||
* The setpoint (SP) is always the first tier of one type; the process variable
|
||
* (PV) is either any tier of the other type or any other tier of the same
|
||
* type.
|
||
*
|
||
* The error is the difference between the SP and the PV; the correction is to
|
||
* turn off protection when SP>PV or turn on protection when SP<PV.
|
||
*
|
||
* For future optimizations:
|
||
* 1. The D term may discount the other two terms over time so that long-lived
|
||
* generations can resist stale information.
|
||
*/
|
||
struct ctrl_pos {
|
||
unsigned long refaulted;
|
||
unsigned long total;
|
||
int gain;
|
||
};
|
||
|
||
static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain,
|
||
struct ctrl_pos *pos)
|
||
{
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int hist = lru_hist_from_seq(lrugen->min_seq[type]);
|
||
|
||
pos->refaulted = lrugen->avg_refaulted[type][tier] +
|
||
atomic_long_read(&lrugen->refaulted[hist][type][tier]);
|
||
pos->total = lrugen->avg_total[type][tier] +
|
||
atomic_long_read(&lrugen->evicted[hist][type][tier]);
|
||
if (tier)
|
||
pos->total += lrugen->protected[hist][type][tier - 1];
|
||
pos->gain = gain;
|
||
}
|
||
|
||
static void reset_ctrl_pos(struct lruvec *lruvec, int type, bool carryover)
|
||
{
|
||
int hist, tier;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
bool clear = carryover ? NR_HIST_GENS == 1 : NR_HIST_GENS > 1;
|
||
unsigned long seq = carryover ? lrugen->min_seq[type] : lrugen->max_seq + 1;
|
||
|
||
lockdep_assert_held(&lruvec->lru_lock);
|
||
|
||
if (!carryover && !clear)
|
||
return;
|
||
|
||
hist = lru_hist_from_seq(seq);
|
||
|
||
for (tier = 0; tier < MAX_NR_TIERS; tier++) {
|
||
if (carryover) {
|
||
unsigned long sum;
|
||
|
||
sum = lrugen->avg_refaulted[type][tier] +
|
||
atomic_long_read(&lrugen->refaulted[hist][type][tier]);
|
||
WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2);
|
||
|
||
sum = lrugen->avg_total[type][tier] +
|
||
atomic_long_read(&lrugen->evicted[hist][type][tier]);
|
||
if (tier)
|
||
sum += lrugen->protected[hist][type][tier - 1];
|
||
WRITE_ONCE(lrugen->avg_total[type][tier], sum / 2);
|
||
}
|
||
|
||
if (clear) {
|
||
atomic_long_set(&lrugen->refaulted[hist][type][tier], 0);
|
||
atomic_long_set(&lrugen->evicted[hist][type][tier], 0);
|
||
if (tier)
|
||
WRITE_ONCE(lrugen->protected[hist][type][tier - 1], 0);
|
||
}
|
||
}
|
||
}
|
||
|
||
static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv)
|
||
{
|
||
/*
|
||
* Return true if the PV has a limited number of refaults or a lower
|
||
* refaulted/total than the SP.
|
||
*/
|
||
return pv->refaulted < MIN_LRU_BATCH ||
|
||
pv->refaulted * (sp->total + MIN_LRU_BATCH) * sp->gain <=
|
||
(sp->refaulted + 1) * pv->total * pv->gain;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* the aging
|
||
******************************************************************************/
|
||
|
||
/* promote pages accessed through page tables */
|
||
static int folio_update_gen(struct folio *folio, int gen)
|
||
{
|
||
unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
|
||
|
||
VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
|
||
VM_WARN_ON_ONCE(!rcu_read_lock_held());
|
||
|
||
do {
|
||
/* lru_gen_del_folio() has isolated this page? */
|
||
if (!(old_flags & LRU_GEN_MASK)) {
|
||
/* for shrink_folio_list() */
|
||
new_flags = old_flags | BIT(PG_referenced);
|
||
continue;
|
||
}
|
||
|
||
new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_MASK | LRU_REFS_FLAGS);
|
||
new_flags |= (gen + 1UL) << LRU_GEN_PGOFF;
|
||
} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
|
||
|
||
return ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
|
||
}
|
||
|
||
/* protect pages accessed multiple times through file descriptors */
|
||
static int folio_inc_gen(struct lruvec *lruvec, struct folio *folio, bool reclaiming)
|
||
{
|
||
int type = folio_is_file_lru(folio);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
|
||
unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(!(old_flags & LRU_GEN_MASK), folio);
|
||
|
||
do {
|
||
new_gen = ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
|
||
/* folio_update_gen() has promoted this page? */
|
||
if (new_gen >= 0 && new_gen != old_gen)
|
||
return new_gen;
|
||
|
||
new_gen = (old_gen + 1) % MAX_NR_GENS;
|
||
|
||
new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_MASK | LRU_REFS_FLAGS);
|
||
new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF;
|
||
/* for folio_end_writeback() */
|
||
if (reclaiming)
|
||
new_flags |= BIT(PG_reclaim);
|
||
} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
|
||
|
||
lru_gen_update_size(lruvec, folio, old_gen, new_gen);
|
||
|
||
return new_gen;
|
||
}
|
||
|
||
static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio,
|
||
int old_gen, int new_gen)
|
||
{
|
||
int type = folio_is_file_lru(folio);
|
||
int zone = folio_zonenum(folio);
|
||
int delta = folio_nr_pages(folio);
|
||
|
||
VM_WARN_ON_ONCE(old_gen >= MAX_NR_GENS);
|
||
VM_WARN_ON_ONCE(new_gen >= MAX_NR_GENS);
|
||
|
||
walk->batched++;
|
||
|
||
walk->nr_pages[old_gen][type][zone] -= delta;
|
||
walk->nr_pages[new_gen][type][zone] += delta;
|
||
}
|
||
|
||
static void reset_batch_size(struct lruvec *lruvec, struct lru_gen_mm_walk *walk)
|
||
{
|
||
int gen, type, zone;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
|
||
walk->batched = 0;
|
||
|
||
for_each_gen_type_zone(gen, type, zone) {
|
||
enum lru_list lru = type * LRU_INACTIVE_FILE;
|
||
int delta = walk->nr_pages[gen][type][zone];
|
||
|
||
if (!delta)
|
||
continue;
|
||
|
||
walk->nr_pages[gen][type][zone] = 0;
|
||
WRITE_ONCE(lrugen->nr_pages[gen][type][zone],
|
||
lrugen->nr_pages[gen][type][zone] + delta);
|
||
|
||
if (lru_gen_is_active(lruvec, gen))
|
||
lru += LRU_ACTIVE;
|
||
__update_lru_size(lruvec, lru, zone, delta);
|
||
}
|
||
}
|
||
|
||
static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *args)
|
||
{
|
||
struct address_space *mapping;
|
||
struct vm_area_struct *vma = args->vma;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
|
||
if (!vma_is_accessible(vma))
|
||
return true;
|
||
|
||
if (is_vm_hugetlb_page(vma))
|
||
return true;
|
||
|
||
if (!vma_has_recency(vma))
|
||
return true;
|
||
|
||
if (vma->vm_flags & (VM_LOCKED | VM_SPECIAL))
|
||
return true;
|
||
|
||
if (vma == get_gate_vma(vma->vm_mm))
|
||
return true;
|
||
|
||
if (vma_is_anonymous(vma))
|
||
return !walk->can_swap;
|
||
|
||
if (WARN_ON_ONCE(!vma->vm_file || !vma->vm_file->f_mapping))
|
||
return true;
|
||
|
||
mapping = vma->vm_file->f_mapping;
|
||
if (mapping_unevictable(mapping))
|
||
return true;
|
||
|
||
if (shmem_mapping(mapping))
|
||
return !walk->can_swap;
|
||
|
||
/* to exclude special mappings like dax, etc. */
|
||
return !mapping->a_ops->read_folio;
|
||
}
|
||
|
||
/*
|
||
* Some userspace memory allocators map many single-page VMAs. Instead of
|
||
* returning back to the PGD table for each of such VMAs, finish an entire PMD
|
||
* table to reduce zigzags and improve cache performance.
|
||
*/
|
||
static bool get_next_vma(unsigned long mask, unsigned long size, struct mm_walk *args,
|
||
unsigned long *vm_start, unsigned long *vm_end)
|
||
{
|
||
unsigned long start = round_up(*vm_end, size);
|
||
unsigned long end = (start | ~mask) + 1;
|
||
VMA_ITERATOR(vmi, args->mm, start);
|
||
|
||
VM_WARN_ON_ONCE(mask & size);
|
||
VM_WARN_ON_ONCE((start & mask) != (*vm_start & mask));
|
||
|
||
for_each_vma(vmi, args->vma) {
|
||
if (end && end <= args->vma->vm_start)
|
||
return false;
|
||
|
||
if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args))
|
||
continue;
|
||
|
||
*vm_start = max(start, args->vma->vm_start);
|
||
*vm_end = min(end - 1, args->vma->vm_end - 1) + 1;
|
||
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned long addr)
|
||
{
|
||
unsigned long pfn = pte_pfn(pte);
|
||
|
||
VM_WARN_ON_ONCE(addr < vma->vm_start || addr >= vma->vm_end);
|
||
|
||
if (!pte_present(pte) || is_zero_pfn(pfn))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(pte_devmap(pte) || pte_special(pte)))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(!pfn_valid(pfn)))
|
||
return -1;
|
||
|
||
return pfn;
|
||
}
|
||
|
||
static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned long addr)
|
||
{
|
||
unsigned long pfn = pmd_pfn(pmd);
|
||
|
||
VM_WARN_ON_ONCE(addr < vma->vm_start || addr >= vma->vm_end);
|
||
|
||
if (!pmd_present(pmd) || is_huge_zero_pmd(pmd))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(pmd_devmap(pmd)))
|
||
return -1;
|
||
|
||
if (WARN_ON_ONCE(!pfn_valid(pfn)))
|
||
return -1;
|
||
|
||
return pfn;
|
||
}
|
||
|
||
static struct folio *get_pfn_folio(unsigned long pfn, struct mem_cgroup *memcg,
|
||
struct pglist_data *pgdat, bool can_swap)
|
||
{
|
||
struct folio *folio;
|
||
|
||
/* try to avoid unnecessary memory loads */
|
||
if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
|
||
return NULL;
|
||
|
||
folio = pfn_folio(pfn);
|
||
if (folio_nid(folio) != pgdat->node_id)
|
||
return NULL;
|
||
|
||
if (folio_memcg_rcu(folio) != memcg)
|
||
return NULL;
|
||
|
||
/* file VMAs can contain anon pages from COW */
|
||
if (!folio_is_file_lru(folio) && !can_swap)
|
||
return NULL;
|
||
|
||
return folio;
|
||
}
|
||
|
||
static bool suitable_to_scan(int total, int young)
|
||
{
|
||
int n = clamp_t(int, cache_line_size() / sizeof(pte_t), 2, 8);
|
||
|
||
/* suitable if the average number of young PTEs per cacheline is >=1 */
|
||
return young * n >= total;
|
||
}
|
||
|
||
static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,
|
||
struct mm_walk *args)
|
||
{
|
||
int i;
|
||
pte_t *pte;
|
||
spinlock_t *ptl;
|
||
unsigned long addr;
|
||
int total = 0;
|
||
int young = 0;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
int old_gen, new_gen = lru_gen_from_seq(walk->max_seq);
|
||
|
||
pte = pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl);
|
||
if (!pte)
|
||
return false;
|
||
if (!spin_trylock(ptl)) {
|
||
pte_unmap(pte);
|
||
return false;
|
||
}
|
||
|
||
arch_enter_lazy_mmu_mode();
|
||
restart:
|
||
for (i = pte_index(start), addr = start; addr != end; i++, addr += PAGE_SIZE) {
|
||
unsigned long pfn;
|
||
struct folio *folio;
|
||
pte_t ptent = ptep_get(pte + i);
|
||
|
||
total++;
|
||
walk->mm_stats[MM_LEAF_TOTAL]++;
|
||
|
||
pfn = get_pte_pfn(ptent, args->vma, addr);
|
||
if (pfn == -1)
|
||
continue;
|
||
|
||
if (!pte_young(ptent)) {
|
||
walk->mm_stats[MM_LEAF_OLD]++;
|
||
continue;
|
||
}
|
||
|
||
folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap);
|
||
if (!folio)
|
||
continue;
|
||
|
||
if (!ptep_test_and_clear_young(args->vma, addr, pte + i))
|
||
VM_WARN_ON_ONCE(true);
|
||
|
||
young++;
|
||
walk->mm_stats[MM_LEAF_YOUNG]++;
|
||
|
||
if (pte_dirty(ptent) && !folio_test_dirty(folio) &&
|
||
!(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
|
||
!folio_test_swapcache(folio)))
|
||
folio_mark_dirty(folio);
|
||
|
||
old_gen = folio_update_gen(folio, new_gen);
|
||
if (old_gen >= 0 && old_gen != new_gen)
|
||
update_batch_size(walk, folio, old_gen, new_gen);
|
||
}
|
||
|
||
if (i < PTRS_PER_PTE && get_next_vma(PMD_MASK, PAGE_SIZE, args, &start, &end))
|
||
goto restart;
|
||
|
||
arch_leave_lazy_mmu_mode();
|
||
pte_unmap_unlock(pte, ptl);
|
||
|
||
return suitable_to_scan(total, young);
|
||
}
|
||
|
||
static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area_struct *vma,
|
||
struct mm_walk *args, unsigned long *bitmap, unsigned long *first)
|
||
{
|
||
int i;
|
||
pmd_t *pmd;
|
||
spinlock_t *ptl;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
struct mem_cgroup *memcg = lruvec_memcg(walk->lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
int old_gen, new_gen = lru_gen_from_seq(walk->max_seq);
|
||
|
||
VM_WARN_ON_ONCE(pud_leaf(*pud));
|
||
|
||
/* try to batch at most 1+MIN_LRU_BATCH+1 entries */
|
||
if (*first == -1) {
|
||
*first = addr;
|
||
bitmap_zero(bitmap, MIN_LRU_BATCH);
|
||
return;
|
||
}
|
||
|
||
i = addr == -1 ? 0 : pmd_index(addr) - pmd_index(*first);
|
||
if (i && i <= MIN_LRU_BATCH) {
|
||
__set_bit(i - 1, bitmap);
|
||
return;
|
||
}
|
||
|
||
pmd = pmd_offset(pud, *first);
|
||
|
||
ptl = pmd_lockptr(args->mm, pmd);
|
||
if (!spin_trylock(ptl))
|
||
goto done;
|
||
|
||
arch_enter_lazy_mmu_mode();
|
||
|
||
do {
|
||
unsigned long pfn;
|
||
struct folio *folio;
|
||
|
||
/* don't round down the first address */
|
||
addr = i ? (*first & PMD_MASK) + i * PMD_SIZE : *first;
|
||
|
||
pfn = get_pmd_pfn(pmd[i], vma, addr);
|
||
if (pfn == -1)
|
||
goto next;
|
||
|
||
if (!pmd_trans_huge(pmd[i])) {
|
||
if (should_clear_pmd_young())
|
||
pmdp_test_and_clear_young(vma, addr, pmd + i);
|
||
goto next;
|
||
}
|
||
|
||
folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap);
|
||
if (!folio)
|
||
goto next;
|
||
|
||
if (!pmdp_test_and_clear_young(vma, addr, pmd + i))
|
||
goto next;
|
||
|
||
walk->mm_stats[MM_LEAF_YOUNG]++;
|
||
|
||
if (pmd_dirty(pmd[i]) && !folio_test_dirty(folio) &&
|
||
!(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
|
||
!folio_test_swapcache(folio)))
|
||
folio_mark_dirty(folio);
|
||
|
||
old_gen = folio_update_gen(folio, new_gen);
|
||
if (old_gen >= 0 && old_gen != new_gen)
|
||
update_batch_size(walk, folio, old_gen, new_gen);
|
||
next:
|
||
i = i > MIN_LRU_BATCH ? 0 : find_next_bit(bitmap, MIN_LRU_BATCH, i) + 1;
|
||
} while (i <= MIN_LRU_BATCH);
|
||
|
||
arch_leave_lazy_mmu_mode();
|
||
spin_unlock(ptl);
|
||
done:
|
||
*first = -1;
|
||
}
|
||
|
||
static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end,
|
||
struct mm_walk *args)
|
||
{
|
||
int i;
|
||
pmd_t *pmd;
|
||
unsigned long next;
|
||
unsigned long addr;
|
||
struct vm_area_struct *vma;
|
||
DECLARE_BITMAP(bitmap, MIN_LRU_BATCH);
|
||
unsigned long first = -1;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(walk->lruvec);
|
||
|
||
VM_WARN_ON_ONCE(pud_leaf(*pud));
|
||
|
||
/*
|
||
* Finish an entire PMD in two passes: the first only reaches to PTE
|
||
* tables to avoid taking the PMD lock; the second, if necessary, takes
|
||
* the PMD lock to clear the accessed bit in PMD entries.
|
||
*/
|
||
pmd = pmd_offset(pud, start & PUD_MASK);
|
||
restart:
|
||
/* walk_pte_range() may call get_next_vma() */
|
||
vma = args->vma;
|
||
for (i = pmd_index(start), addr = start; addr != end; i++, addr = next) {
|
||
pmd_t val = pmdp_get_lockless(pmd + i);
|
||
|
||
next = pmd_addr_end(addr, end);
|
||
|
||
if (!pmd_present(val) || is_huge_zero_pmd(val)) {
|
||
walk->mm_stats[MM_LEAF_TOTAL]++;
|
||
continue;
|
||
}
|
||
|
||
if (pmd_trans_huge(val)) {
|
||
unsigned long pfn = pmd_pfn(val);
|
||
struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec);
|
||
|
||
walk->mm_stats[MM_LEAF_TOTAL]++;
|
||
|
||
if (!pmd_young(val)) {
|
||
walk->mm_stats[MM_LEAF_OLD]++;
|
||
continue;
|
||
}
|
||
|
||
/* try to avoid unnecessary memory loads */
|
||
if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
|
||
continue;
|
||
|
||
walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first);
|
||
continue;
|
||
}
|
||
|
||
walk->mm_stats[MM_NONLEAF_TOTAL]++;
|
||
|
||
if (should_clear_pmd_young()) {
|
||
if (!pmd_young(val))
|
||
continue;
|
||
|
||
walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first);
|
||
}
|
||
|
||
if (!walk->force_scan && !test_bloom_filter(mm_state, walk->max_seq, pmd + i))
|
||
continue;
|
||
|
||
walk->mm_stats[MM_NONLEAF_FOUND]++;
|
||
|
||
if (!walk_pte_range(&val, addr, next, args))
|
||
continue;
|
||
|
||
walk->mm_stats[MM_NONLEAF_ADDED]++;
|
||
|
||
/* carry over to the next generation */
|
||
update_bloom_filter(mm_state, walk->max_seq + 1, pmd + i);
|
||
}
|
||
|
||
walk_pmd_range_locked(pud, -1, vma, args, bitmap, &first);
|
||
|
||
if (i < PTRS_PER_PMD && get_next_vma(PUD_MASK, PMD_SIZE, args, &start, &end))
|
||
goto restart;
|
||
}
|
||
|
||
static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end,
|
||
struct mm_walk *args)
|
||
{
|
||
int i;
|
||
pud_t *pud;
|
||
unsigned long addr;
|
||
unsigned long next;
|
||
struct lru_gen_mm_walk *walk = args->private;
|
||
|
||
VM_WARN_ON_ONCE(p4d_leaf(*p4d));
|
||
|
||
pud = pud_offset(p4d, start & P4D_MASK);
|
||
restart:
|
||
for (i = pud_index(start), addr = start; addr != end; i++, addr = next) {
|
||
pud_t val = READ_ONCE(pud[i]);
|
||
|
||
next = pud_addr_end(addr, end);
|
||
|
||
if (!pud_present(val) || WARN_ON_ONCE(pud_leaf(val)))
|
||
continue;
|
||
|
||
walk_pmd_range(&val, addr, next, args);
|
||
|
||
if (need_resched() || walk->batched >= MAX_LRU_BATCH) {
|
||
end = (addr | ~PUD_MASK) + 1;
|
||
goto done;
|
||
}
|
||
}
|
||
|
||
if (i < PTRS_PER_PUD && get_next_vma(P4D_MASK, PUD_SIZE, args, &start, &end))
|
||
goto restart;
|
||
|
||
end = round_up(end, P4D_SIZE);
|
||
done:
|
||
if (!end || !args->vma)
|
||
return 1;
|
||
|
||
walk->next_addr = max(end, args->vma->vm_start);
|
||
|
||
return -EAGAIN;
|
||
}
|
||
|
||
static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct lru_gen_mm_walk *walk)
|
||
{
|
||
static const struct mm_walk_ops mm_walk_ops = {
|
||
.test_walk = should_skip_vma,
|
||
.p4d_entry = walk_pud_range,
|
||
.walk_lock = PGWALK_RDLOCK,
|
||
};
|
||
|
||
int err;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
|
||
walk->next_addr = FIRST_USER_ADDRESS;
|
||
|
||
do {
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
|
||
err = -EBUSY;
|
||
|
||
/* another thread might have called inc_max_seq() */
|
||
if (walk->max_seq != max_seq)
|
||
break;
|
||
|
||
/* folio_update_gen() requires stable folio_memcg() */
|
||
if (!mem_cgroup_trylock_pages(memcg))
|
||
break;
|
||
|
||
/* the caller might be holding the lock for write */
|
||
if (mmap_read_trylock(mm)) {
|
||
err = walk_page_range(mm, walk->next_addr, ULONG_MAX, &mm_walk_ops, walk);
|
||
|
||
mmap_read_unlock(mm);
|
||
}
|
||
|
||
mem_cgroup_unlock_pages();
|
||
|
||
if (walk->batched) {
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
reset_batch_size(lruvec, walk);
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
cond_resched();
|
||
} while (err == -EAGAIN);
|
||
}
|
||
|
||
static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc)
|
||
{
|
||
struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk;
|
||
|
||
if (pgdat && current_is_kswapd()) {
|
||
VM_WARN_ON_ONCE(walk);
|
||
|
||
walk = &pgdat->mm_walk;
|
||
} else if (!walk && force_alloc) {
|
||
VM_WARN_ON_ONCE(current_is_kswapd());
|
||
|
||
walk = kzalloc(sizeof(*walk), __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
||
}
|
||
|
||
current->reclaim_state->mm_walk = walk;
|
||
|
||
return walk;
|
||
}
|
||
|
||
static void clear_mm_walk(void)
|
||
{
|
||
struct lru_gen_mm_walk *walk = current->reclaim_state->mm_walk;
|
||
|
||
VM_WARN_ON_ONCE(walk && memchr_inv(walk->nr_pages, 0, sizeof(walk->nr_pages)));
|
||
VM_WARN_ON_ONCE(walk && memchr_inv(walk->mm_stats, 0, sizeof(walk->mm_stats)));
|
||
|
||
current->reclaim_state->mm_walk = NULL;
|
||
|
||
if (!current_is_kswapd())
|
||
kfree(walk);
|
||
}
|
||
|
||
static bool inc_min_seq(struct lruvec *lruvec, int type, bool can_swap)
|
||
{
|
||
int zone;
|
||
int remaining = MAX_LRU_BATCH;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
|
||
|
||
if (type == LRU_GEN_ANON && !can_swap)
|
||
goto done;
|
||
|
||
/* prevent cold/hot inversion if force_scan is true */
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
|
||
struct list_head *head = &lrugen->folios[old_gen][type][zone];
|
||
|
||
while (!list_empty(head)) {
|
||
struct folio *folio = lru_to_folio(head);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
|
||
|
||
new_gen = folio_inc_gen(lruvec, folio, false);
|
||
list_move_tail(&folio->lru, &lrugen->folios[new_gen][type][zone]);
|
||
|
||
if (!--remaining)
|
||
return false;
|
||
}
|
||
}
|
||
done:
|
||
reset_ctrl_pos(lruvec, type, true);
|
||
WRITE_ONCE(lrugen->min_seq[type], lrugen->min_seq[type] + 1);
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool try_to_inc_min_seq(struct lruvec *lruvec, bool can_swap)
|
||
{
|
||
int gen, type, zone;
|
||
bool success = false;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
|
||
|
||
/* find the oldest populated generation */
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
while (min_seq[type] + MIN_NR_GENS <= lrugen->max_seq) {
|
||
gen = lru_gen_from_seq(min_seq[type]);
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
|
||
if (!list_empty(&lrugen->folios[gen][type][zone]))
|
||
goto next;
|
||
}
|
||
|
||
min_seq[type]++;
|
||
}
|
||
next:
|
||
;
|
||
}
|
||
|
||
/* see the comment on lru_gen_folio */
|
||
if (can_swap) {
|
||
min_seq[LRU_GEN_ANON] = min(min_seq[LRU_GEN_ANON], min_seq[LRU_GEN_FILE]);
|
||
min_seq[LRU_GEN_FILE] = max(min_seq[LRU_GEN_ANON], lrugen->min_seq[LRU_GEN_FILE]);
|
||
}
|
||
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
if (min_seq[type] == lrugen->min_seq[type])
|
||
continue;
|
||
|
||
reset_ctrl_pos(lruvec, type, true);
|
||
WRITE_ONCE(lrugen->min_seq[type], min_seq[type]);
|
||
success = true;
|
||
}
|
||
|
||
return success;
|
||
}
|
||
|
||
static bool inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
|
||
bool can_swap, bool force_scan)
|
||
{
|
||
bool success;
|
||
int prev, next;
|
||
int type, zone;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
restart:
|
||
if (max_seq < READ_ONCE(lrugen->max_seq))
|
||
return false;
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
|
||
|
||
success = max_seq == lrugen->max_seq;
|
||
if (!success)
|
||
goto unlock;
|
||
|
||
for (type = ANON_AND_FILE - 1; type >= 0; type--) {
|
||
if (get_nr_gens(lruvec, type) != MAX_NR_GENS)
|
||
continue;
|
||
|
||
VM_WARN_ON_ONCE(!force_scan && (type == LRU_GEN_FILE || can_swap));
|
||
|
||
if (inc_min_seq(lruvec, type, can_swap))
|
||
continue;
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
cond_resched();
|
||
goto restart;
|
||
}
|
||
|
||
/*
|
||
* Update the active/inactive LRU sizes for compatibility. Both sides of
|
||
* the current max_seq need to be covered, since max_seq+1 can overlap
|
||
* with min_seq[LRU_GEN_ANON] if swapping is constrained. And if they do
|
||
* overlap, cold/hot inversion happens.
|
||
*/
|
||
prev = lru_gen_from_seq(lrugen->max_seq - 1);
|
||
next = lru_gen_from_seq(lrugen->max_seq + 1);
|
||
|
||
for (type = 0; type < ANON_AND_FILE; type++) {
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
|
||
enum lru_list lru = type * LRU_INACTIVE_FILE;
|
||
long delta = lrugen->nr_pages[prev][type][zone] -
|
||
lrugen->nr_pages[next][type][zone];
|
||
|
||
if (!delta)
|
||
continue;
|
||
|
||
__update_lru_size(lruvec, lru, zone, delta);
|
||
__update_lru_size(lruvec, lru + LRU_ACTIVE, zone, -delta);
|
||
}
|
||
}
|
||
|
||
for (type = 0; type < ANON_AND_FILE; type++)
|
||
reset_ctrl_pos(lruvec, type, false);
|
||
|
||
WRITE_ONCE(lrugen->timestamps[next], jiffies);
|
||
/* make sure preceding modifications appear */
|
||
smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1);
|
||
unlock:
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
return success;
|
||
}
|
||
|
||
static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
|
||
struct scan_control *sc, bool can_swap, bool force_scan)
|
||
{
|
||
bool success;
|
||
struct lru_gen_mm_walk *walk;
|
||
struct mm_struct *mm = NULL;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(max_seq > READ_ONCE(lrugen->max_seq));
|
||
|
||
if (!mm_state)
|
||
return inc_max_seq(lruvec, max_seq, can_swap, force_scan);
|
||
|
||
/* see the comment in iterate_mm_list() */
|
||
if (max_seq <= READ_ONCE(mm_state->seq))
|
||
return false;
|
||
|
||
/*
|
||
* If the hardware doesn't automatically set the accessed bit, fallback
|
||
* to lru_gen_look_around(), which only clears the accessed bit in a
|
||
* handful of PTEs. Spreading the work out over a period of time usually
|
||
* is less efficient, but it avoids bursty page faults.
|
||
*/
|
||
if (!should_walk_mmu()) {
|
||
success = iterate_mm_list_nowalk(lruvec, max_seq);
|
||
goto done;
|
||
}
|
||
|
||
walk = set_mm_walk(NULL, true);
|
||
if (!walk) {
|
||
success = iterate_mm_list_nowalk(lruvec, max_seq);
|
||
goto done;
|
||
}
|
||
|
||
walk->lruvec = lruvec;
|
||
walk->max_seq = max_seq;
|
||
walk->can_swap = can_swap;
|
||
walk->force_scan = force_scan;
|
||
|
||
do {
|
||
success = iterate_mm_list(lruvec, walk, &mm);
|
||
if (mm)
|
||
walk_mm(lruvec, mm, walk);
|
||
} while (mm);
|
||
done:
|
||
if (success) {
|
||
success = inc_max_seq(lruvec, max_seq, can_swap, force_scan);
|
||
WARN_ON_ONCE(!success);
|
||
}
|
||
|
||
return success;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* working set protection
|
||
******************************************************************************/
|
||
|
||
static bool lruvec_is_sizable(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
int gen, type, zone;
|
||
unsigned long total = 0;
|
||
bool can_swap = get_swappiness(lruvec, sc);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
unsigned long seq;
|
||
|
||
for (seq = min_seq[type]; seq <= max_seq; seq++) {
|
||
gen = lru_gen_from_seq(seq);
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++)
|
||
total += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
|
||
}
|
||
}
|
||
|
||
/* whether the size is big enough to be helpful */
|
||
return mem_cgroup_online(memcg) ? (total >> sc->priority) : total;
|
||
}
|
||
|
||
static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc,
|
||
unsigned long min_ttl)
|
||
{
|
||
int gen;
|
||
unsigned long birth;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
/* see the comment on lru_gen_folio */
|
||
gen = lru_gen_from_seq(min_seq[LRU_GEN_FILE]);
|
||
birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
|
||
|
||
if (time_is_after_jiffies(birth + min_ttl))
|
||
return false;
|
||
|
||
if (!lruvec_is_sizable(lruvec, sc))
|
||
return false;
|
||
|
||
mem_cgroup_calculate_protection(NULL, memcg);
|
||
|
||
return !mem_cgroup_below_min(NULL, memcg);
|
||
}
|
||
|
||
/* to protect the working set of the last N jiffies */
|
||
static unsigned long lru_gen_min_ttl __read_mostly;
|
||
|
||
static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
unsigned long min_ttl = READ_ONCE(lru_gen_min_ttl);
|
||
|
||
VM_WARN_ON_ONCE(!current_is_kswapd());
|
||
|
||
/* check the order to exclude compaction-induced reclaim */
|
||
if (!min_ttl || sc->order || sc->priority == DEF_PRIORITY)
|
||
return;
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
|
||
if (lruvec_is_reclaimable(lruvec, sc, min_ttl)) {
|
||
mem_cgroup_iter_break(NULL, memcg);
|
||
return;
|
||
}
|
||
|
||
cond_resched();
|
||
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
|
||
|
||
/*
|
||
* The main goal is to OOM kill if every generation from all memcgs is
|
||
* younger than min_ttl. However, another possibility is all memcgs are
|
||
* either too small or below min.
|
||
*/
|
||
if (mutex_trylock(&oom_lock)) {
|
||
struct oom_control oc = {
|
||
.gfp_mask = sc->gfp_mask,
|
||
};
|
||
|
||
out_of_memory(&oc);
|
||
|
||
mutex_unlock(&oom_lock);
|
||
}
|
||
}
|
||
|
||
/******************************************************************************
|
||
* rmap/PT walk feedback
|
||
******************************************************************************/
|
||
|
||
/*
|
||
* This function exploits spatial locality when shrink_folio_list() walks the
|
||
* rmap. It scans the adjacent PTEs of a young PTE and promotes hot pages. If
|
||
* the scan was done cacheline efficiently, it adds the PMD entry pointing to
|
||
* the PTE table to the Bloom filter. This forms a feedback loop between the
|
||
* eviction and the aging.
|
||
*/
|
||
void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
|
||
{
|
||
int i;
|
||
unsigned long start;
|
||
unsigned long end;
|
||
struct lru_gen_mm_walk *walk;
|
||
int young = 0;
|
||
pte_t *pte = pvmw->pte;
|
||
unsigned long addr = pvmw->address;
|
||
struct vm_area_struct *vma = pvmw->vma;
|
||
struct folio *folio = pfn_folio(pvmw->pfn);
|
||
bool can_swap = !folio_is_file_lru(folio);
|
||
struct mem_cgroup *memcg = folio_memcg(folio);
|
||
struct pglist_data *pgdat = folio_pgdat(folio);
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
int old_gen, new_gen = lru_gen_from_seq(max_seq);
|
||
|
||
lockdep_assert_held(pvmw->ptl);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);
|
||
|
||
if (spin_is_contended(pvmw->ptl))
|
||
return;
|
||
|
||
/* exclude special VMAs containing anon pages from COW */
|
||
if (vma->vm_flags & VM_SPECIAL)
|
||
return;
|
||
|
||
/* avoid taking the LRU lock under the PTL when possible */
|
||
walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL;
|
||
|
||
start = max(addr & PMD_MASK, vma->vm_start);
|
||
end = min(addr | ~PMD_MASK, vma->vm_end - 1) + 1;
|
||
|
||
if (end - start > MIN_LRU_BATCH * PAGE_SIZE) {
|
||
if (addr - start < MIN_LRU_BATCH * PAGE_SIZE / 2)
|
||
end = start + MIN_LRU_BATCH * PAGE_SIZE;
|
||
else if (end - addr < MIN_LRU_BATCH * PAGE_SIZE / 2)
|
||
start = end - MIN_LRU_BATCH * PAGE_SIZE;
|
||
else {
|
||
start = addr - MIN_LRU_BATCH * PAGE_SIZE / 2;
|
||
end = addr + MIN_LRU_BATCH * PAGE_SIZE / 2;
|
||
}
|
||
}
|
||
|
||
/* folio_update_gen() requires stable folio_memcg() */
|
||
if (!mem_cgroup_trylock_pages(memcg))
|
||
return;
|
||
|
||
arch_enter_lazy_mmu_mode();
|
||
|
||
pte -= (addr - start) / PAGE_SIZE;
|
||
|
||
for (i = 0, addr = start; addr != end; i++, addr += PAGE_SIZE) {
|
||
unsigned long pfn;
|
||
pte_t ptent = ptep_get(pte + i);
|
||
|
||
pfn = get_pte_pfn(ptent, vma, addr);
|
||
if (pfn == -1)
|
||
continue;
|
||
|
||
if (!pte_young(ptent))
|
||
continue;
|
||
|
||
folio = get_pfn_folio(pfn, memcg, pgdat, can_swap);
|
||
if (!folio)
|
||
continue;
|
||
|
||
if (!ptep_test_and_clear_young(vma, addr, pte + i))
|
||
VM_WARN_ON_ONCE(true);
|
||
|
||
young++;
|
||
|
||
if (pte_dirty(ptent) && !folio_test_dirty(folio) &&
|
||
!(folio_test_anon(folio) && folio_test_swapbacked(folio) &&
|
||
!folio_test_swapcache(folio)))
|
||
folio_mark_dirty(folio);
|
||
|
||
if (walk) {
|
||
old_gen = folio_update_gen(folio, new_gen);
|
||
if (old_gen >= 0 && old_gen != new_gen)
|
||
update_batch_size(walk, folio, old_gen, new_gen);
|
||
|
||
continue;
|
||
}
|
||
|
||
old_gen = folio_lru_gen(folio);
|
||
if (old_gen < 0)
|
||
folio_set_referenced(folio);
|
||
else if (old_gen != new_gen)
|
||
folio_activate(folio);
|
||
}
|
||
|
||
arch_leave_lazy_mmu_mode();
|
||
mem_cgroup_unlock_pages();
|
||
|
||
/* feedback from rmap walkers to page table walkers */
|
||
if (mm_state && suitable_to_scan(i, young))
|
||
update_bloom_filter(mm_state, max_seq, pvmw->pmd);
|
||
}
|
||
|
||
/******************************************************************************
|
||
* memcg LRU
|
||
******************************************************************************/
|
||
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
enum {
|
||
MEMCG_LRU_NOP,
|
||
MEMCG_LRU_HEAD,
|
||
MEMCG_LRU_TAIL,
|
||
MEMCG_LRU_OLD,
|
||
MEMCG_LRU_YOUNG,
|
||
};
|
||
|
||
static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)
|
||
{
|
||
int seg;
|
||
int old, new;
|
||
unsigned long flags;
|
||
int bin = get_random_u32_below(MEMCG_NR_BINS);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
spin_lock_irqsave(&pgdat->memcg_lru.lock, flags);
|
||
|
||
VM_WARN_ON_ONCE(hlist_nulls_unhashed(&lruvec->lrugen.list));
|
||
|
||
seg = 0;
|
||
new = old = lruvec->lrugen.gen;
|
||
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
if (op == MEMCG_LRU_HEAD)
|
||
seg = MEMCG_LRU_HEAD;
|
||
else if (op == MEMCG_LRU_TAIL)
|
||
seg = MEMCG_LRU_TAIL;
|
||
else if (op == MEMCG_LRU_OLD)
|
||
new = get_memcg_gen(pgdat->memcg_lru.seq);
|
||
else if (op == MEMCG_LRU_YOUNG)
|
||
new = get_memcg_gen(pgdat->memcg_lru.seq + 1);
|
||
else
|
||
VM_WARN_ON_ONCE(true);
|
||
|
||
WRITE_ONCE(lruvec->lrugen.seg, seg);
|
||
WRITE_ONCE(lruvec->lrugen.gen, new);
|
||
|
||
hlist_nulls_del_rcu(&lruvec->lrugen.list);
|
||
|
||
if (op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD)
|
||
hlist_nulls_add_head_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
|
||
else
|
||
hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]);
|
||
|
||
pgdat->memcg_lru.nr_memcgs[old]--;
|
||
pgdat->memcg_lru.nr_memcgs[new]++;
|
||
|
||
if (!pgdat->memcg_lru.nr_memcgs[old] && old == get_memcg_gen(pgdat->memcg_lru.seq))
|
||
WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1);
|
||
|
||
spin_unlock_irqrestore(&pgdat->memcg_lru.lock, flags);
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
|
||
void lru_gen_online_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int gen;
|
||
int nid;
|
||
int bin = get_random_u32_below(MEMCG_NR_BINS);
|
||
|
||
for_each_node(nid) {
|
||
struct pglist_data *pgdat = NODE_DATA(nid);
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
spin_lock_irq(&pgdat->memcg_lru.lock);
|
||
|
||
VM_WARN_ON_ONCE(!hlist_nulls_unhashed(&lruvec->lrugen.list));
|
||
|
||
gen = get_memcg_gen(pgdat->memcg_lru.seq);
|
||
|
||
lruvec->lrugen.gen = gen;
|
||
|
||
hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[gen][bin]);
|
||
pgdat->memcg_lru.nr_memcgs[gen]++;
|
||
|
||
spin_unlock_irq(&pgdat->memcg_lru.lock);
|
||
}
|
||
}
|
||
|
||
void lru_gen_offline_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int nid;
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
lru_gen_rotate_memcg(lruvec, MEMCG_LRU_OLD);
|
||
}
|
||
}
|
||
|
||
void lru_gen_release_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int gen;
|
||
int nid;
|
||
|
||
for_each_node(nid) {
|
||
struct pglist_data *pgdat = NODE_DATA(nid);
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
spin_lock_irq(&pgdat->memcg_lru.lock);
|
||
|
||
if (hlist_nulls_unhashed(&lruvec->lrugen.list))
|
||
goto unlock;
|
||
|
||
gen = lruvec->lrugen.gen;
|
||
|
||
hlist_nulls_del_init_rcu(&lruvec->lrugen.list);
|
||
pgdat->memcg_lru.nr_memcgs[gen]--;
|
||
|
||
if (!pgdat->memcg_lru.nr_memcgs[gen] && gen == get_memcg_gen(pgdat->memcg_lru.seq))
|
||
WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1);
|
||
unlock:
|
||
spin_unlock_irq(&pgdat->memcg_lru.lock);
|
||
}
|
||
}
|
||
|
||
void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid)
|
||
{
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_HEAD)
|
||
lru_gen_rotate_memcg(lruvec, MEMCG_LRU_HEAD);
|
||
}
|
||
|
||
#endif /* CONFIG_MEMCG */
|
||
|
||
/******************************************************************************
|
||
* the eviction
|
||
******************************************************************************/
|
||
|
||
static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc,
|
||
int tier_idx)
|
||
{
|
||
bool success;
|
||
int gen = folio_lru_gen(folio);
|
||
int type = folio_is_file_lru(folio);
|
||
int zone = folio_zonenum(folio);
|
||
int delta = folio_nr_pages(folio);
|
||
int refs = folio_lru_refs(folio);
|
||
int tier = lru_tier_from_refs(refs);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(gen >= MAX_NR_GENS, folio);
|
||
|
||
/* unevictable */
|
||
if (!folio_evictable(folio)) {
|
||
success = lru_gen_del_folio(lruvec, folio, true);
|
||
VM_WARN_ON_ONCE_FOLIO(!success, folio);
|
||
folio_set_unevictable(folio);
|
||
lruvec_add_folio(lruvec, folio);
|
||
__count_vm_events(UNEVICTABLE_PGCULLED, delta);
|
||
return true;
|
||
}
|
||
|
||
/* dirty lazyfree */
|
||
if (type == LRU_GEN_FILE && folio_test_anon(folio) && folio_test_dirty(folio)) {
|
||
success = lru_gen_del_folio(lruvec, folio, true);
|
||
VM_WARN_ON_ONCE_FOLIO(!success, folio);
|
||
folio_set_swapbacked(folio);
|
||
lruvec_add_folio_tail(lruvec, folio);
|
||
return true;
|
||
}
|
||
|
||
/* promoted */
|
||
if (gen != lru_gen_from_seq(lrugen->min_seq[type])) {
|
||
list_move(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
return true;
|
||
}
|
||
|
||
/* protected */
|
||
if (tier > tier_idx || refs == BIT(LRU_REFS_WIDTH)) {
|
||
int hist = lru_hist_from_seq(lrugen->min_seq[type]);
|
||
|
||
gen = folio_inc_gen(lruvec, folio, false);
|
||
list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
|
||
WRITE_ONCE(lrugen->protected[hist][type][tier - 1],
|
||
lrugen->protected[hist][type][tier - 1] + delta);
|
||
return true;
|
||
}
|
||
|
||
/* ineligible */
|
||
if (zone > sc->reclaim_idx || skip_cma(folio, sc)) {
|
||
gen = folio_inc_gen(lruvec, folio, false);
|
||
list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
return true;
|
||
}
|
||
|
||
/* waiting for writeback */
|
||
if (folio_test_locked(folio) || folio_test_writeback(folio) ||
|
||
(type == LRU_GEN_FILE && folio_test_dirty(folio))) {
|
||
gen = folio_inc_gen(lruvec, folio, true);
|
||
list_move(&folio->lru, &lrugen->folios[gen][type][zone]);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc)
|
||
{
|
||
bool success;
|
||
|
||
/* swapping inhibited */
|
||
if (!(sc->gfp_mask & __GFP_IO) &&
|
||
(folio_test_dirty(folio) ||
|
||
(folio_test_anon(folio) && !folio_test_swapcache(folio))))
|
||
return false;
|
||
|
||
/* raced with release_pages() */
|
||
if (!folio_try_get(folio))
|
||
return false;
|
||
|
||
/* raced with another isolation */
|
||
if (!folio_test_clear_lru(folio)) {
|
||
folio_put(folio);
|
||
return false;
|
||
}
|
||
|
||
/* see the comment on MAX_NR_TIERS */
|
||
if (!folio_test_referenced(folio))
|
||
set_mask_bits(&folio->flags, LRU_REFS_MASK | LRU_REFS_FLAGS, 0);
|
||
|
||
/* for shrink_folio_list() */
|
||
folio_clear_reclaim(folio);
|
||
folio_clear_referenced(folio);
|
||
|
||
success = lru_gen_del_folio(lruvec, folio, true);
|
||
VM_WARN_ON_ONCE_FOLIO(!success, folio);
|
||
|
||
return true;
|
||
}
|
||
|
||
static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
|
||
int type, int tier, struct list_head *list)
|
||
{
|
||
int i;
|
||
int gen;
|
||
enum vm_event_item item;
|
||
int sorted = 0;
|
||
int scanned = 0;
|
||
int isolated = 0;
|
||
int skipped = 0;
|
||
int remaining = MAX_LRU_BATCH;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(!list_empty(list));
|
||
|
||
if (get_nr_gens(lruvec, type) == MIN_NR_GENS)
|
||
return 0;
|
||
|
||
gen = lru_gen_from_seq(lrugen->min_seq[type]);
|
||
|
||
for (i = MAX_NR_ZONES; i > 0; i--) {
|
||
LIST_HEAD(moved);
|
||
int skipped_zone = 0;
|
||
int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES;
|
||
struct list_head *head = &lrugen->folios[gen][type][zone];
|
||
|
||
while (!list_empty(head)) {
|
||
struct folio *folio = lru_to_folio(head);
|
||
int delta = folio_nr_pages(folio);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
|
||
|
||
scanned += delta;
|
||
|
||
if (sort_folio(lruvec, folio, sc, tier))
|
||
sorted += delta;
|
||
else if (isolate_folio(lruvec, folio, sc)) {
|
||
list_add(&folio->lru, list);
|
||
isolated += delta;
|
||
} else {
|
||
list_move(&folio->lru, &moved);
|
||
skipped_zone += delta;
|
||
}
|
||
|
||
if (!--remaining || max(isolated, skipped_zone) >= MIN_LRU_BATCH)
|
||
break;
|
||
}
|
||
|
||
if (skipped_zone) {
|
||
list_splice(&moved, head);
|
||
__count_zid_vm_events(PGSCAN_SKIP, zone, skipped_zone);
|
||
skipped += skipped_zone;
|
||
}
|
||
|
||
if (!remaining || isolated >= MIN_LRU_BATCH)
|
||
break;
|
||
}
|
||
|
||
item = PGSCAN_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc)) {
|
||
__count_vm_events(item, isolated);
|
||
__count_vm_events(PGREFILL, sorted);
|
||
}
|
||
__count_memcg_events(memcg, item, isolated);
|
||
__count_memcg_events(memcg, PGREFILL, sorted);
|
||
__count_vm_events(PGSCAN_ANON + type, isolated);
|
||
trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, MAX_LRU_BATCH,
|
||
scanned, skipped, isolated,
|
||
type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
|
||
|
||
/*
|
||
* There might not be eligible folios due to reclaim_idx. Check the
|
||
* remaining to prevent livelock if it's not making progress.
|
||
*/
|
||
return isolated || !remaining ? scanned : 0;
|
||
}
|
||
|
||
static int get_tier_idx(struct lruvec *lruvec, int type)
|
||
{
|
||
int tier;
|
||
struct ctrl_pos sp, pv;
|
||
|
||
/*
|
||
* To leave a margin for fluctuations, use a larger gain factor (1:2).
|
||
* This value is chosen because any other tier would have at least twice
|
||
* as many refaults as the first tier.
|
||
*/
|
||
read_ctrl_pos(lruvec, type, 0, 1, &sp);
|
||
for (tier = 1; tier < MAX_NR_TIERS; tier++) {
|
||
read_ctrl_pos(lruvec, type, tier, 2, &pv);
|
||
if (!positive_ctrl_err(&sp, &pv))
|
||
break;
|
||
}
|
||
|
||
return tier - 1;
|
||
}
|
||
|
||
static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx)
|
||
{
|
||
int type, tier;
|
||
struct ctrl_pos sp, pv;
|
||
int gain[ANON_AND_FILE] = { swappiness, 200 - swappiness };
|
||
|
||
/*
|
||
* Compare the first tier of anon with that of file to determine which
|
||
* type to scan. Also need to compare other tiers of the selected type
|
||
* with the first tier of the other type to determine the last tier (of
|
||
* the selected type) to evict.
|
||
*/
|
||
read_ctrl_pos(lruvec, LRU_GEN_ANON, 0, gain[LRU_GEN_ANON], &sp);
|
||
read_ctrl_pos(lruvec, LRU_GEN_FILE, 0, gain[LRU_GEN_FILE], &pv);
|
||
type = positive_ctrl_err(&sp, &pv);
|
||
|
||
read_ctrl_pos(lruvec, !type, 0, gain[!type], &sp);
|
||
for (tier = 1; tier < MAX_NR_TIERS; tier++) {
|
||
read_ctrl_pos(lruvec, type, tier, gain[type], &pv);
|
||
if (!positive_ctrl_err(&sp, &pv))
|
||
break;
|
||
}
|
||
|
||
*tier_idx = tier - 1;
|
||
|
||
return type;
|
||
}
|
||
|
||
static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness,
|
||
int *type_scanned, struct list_head *list)
|
||
{
|
||
int i;
|
||
int type;
|
||
int scanned;
|
||
int tier = -1;
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
/*
|
||
* Try to make the obvious choice first. When anon and file are both
|
||
* available from the same generation, interpret swappiness 1 as file
|
||
* first and 200 as anon first.
|
||
*/
|
||
if (!swappiness)
|
||
type = LRU_GEN_FILE;
|
||
else if (min_seq[LRU_GEN_ANON] < min_seq[LRU_GEN_FILE])
|
||
type = LRU_GEN_ANON;
|
||
else if (swappiness == 1)
|
||
type = LRU_GEN_FILE;
|
||
else if (swappiness == 200)
|
||
type = LRU_GEN_ANON;
|
||
else
|
||
type = get_type_to_scan(lruvec, swappiness, &tier);
|
||
|
||
for (i = !swappiness; i < ANON_AND_FILE; i++) {
|
||
if (tier < 0)
|
||
tier = get_tier_idx(lruvec, type);
|
||
|
||
scanned = scan_folios(lruvec, sc, type, tier, list);
|
||
if (scanned)
|
||
break;
|
||
|
||
type = !type;
|
||
tier = -1;
|
||
}
|
||
|
||
*type_scanned = type;
|
||
|
||
return scanned;
|
||
}
|
||
|
||
static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness)
|
||
{
|
||
int type;
|
||
int scanned;
|
||
int reclaimed;
|
||
LIST_HEAD(list);
|
||
LIST_HEAD(clean);
|
||
struct folio *folio;
|
||
struct folio *next;
|
||
enum vm_event_item item;
|
||
struct reclaim_stat stat;
|
||
struct lru_gen_mm_walk *walk;
|
||
bool skip_retry = false;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
scanned = isolate_folios(lruvec, sc, swappiness, &type, &list);
|
||
|
||
scanned += try_to_inc_min_seq(lruvec, swappiness);
|
||
|
||
if (get_nr_gens(lruvec, !swappiness) == MIN_NR_GENS)
|
||
scanned = 0;
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
if (list_empty(&list))
|
||
return scanned;
|
||
retry:
|
||
reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false);
|
||
sc->nr_reclaimed += reclaimed;
|
||
trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id,
|
||
scanned, reclaimed, &stat, sc->priority,
|
||
type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON);
|
||
|
||
list_for_each_entry_safe_reverse(folio, next, &list, lru) {
|
||
if (!folio_evictable(folio)) {
|
||
list_del(&folio->lru);
|
||
folio_putback_lru(folio);
|
||
continue;
|
||
}
|
||
|
||
if (folio_test_reclaim(folio) &&
|
||
(folio_test_dirty(folio) || folio_test_writeback(folio))) {
|
||
/* restore LRU_REFS_FLAGS cleared by isolate_folio() */
|
||
if (folio_test_workingset(folio))
|
||
folio_set_referenced(folio);
|
||
continue;
|
||
}
|
||
|
||
if (skip_retry || folio_test_active(folio) || folio_test_referenced(folio) ||
|
||
folio_mapped(folio) || folio_test_locked(folio) ||
|
||
folio_test_dirty(folio) || folio_test_writeback(folio)) {
|
||
/* don't add rejected folios to the oldest generation */
|
||
set_mask_bits(&folio->flags, LRU_REFS_MASK | LRU_REFS_FLAGS,
|
||
BIT(PG_active));
|
||
continue;
|
||
}
|
||
|
||
/* retry folios that may have missed folio_rotate_reclaimable() */
|
||
list_move(&folio->lru, &clean);
|
||
sc->nr_scanned -= folio_nr_pages(folio);
|
||
}
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
move_folios_to_lru(lruvec, &list);
|
||
|
||
walk = current->reclaim_state->mm_walk;
|
||
if (walk && walk->batched)
|
||
reset_batch_size(lruvec, walk);
|
||
|
||
item = PGSTEAL_KSWAPD + reclaimer_offset();
|
||
if (!cgroup_reclaim(sc))
|
||
__count_vm_events(item, reclaimed);
|
||
__count_memcg_events(memcg, item, reclaimed);
|
||
__count_vm_events(PGSTEAL_ANON + type, reclaimed);
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
|
||
mem_cgroup_uncharge_list(&list);
|
||
free_unref_page_list(&list);
|
||
|
||
INIT_LIST_HEAD(&list);
|
||
list_splice_init(&clean, &list);
|
||
|
||
if (!list_empty(&list)) {
|
||
skip_retry = true;
|
||
goto retry;
|
||
}
|
||
|
||
return scanned;
|
||
}
|
||
|
||
static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq,
|
||
struct scan_control *sc, bool can_swap, unsigned long *nr_to_scan)
|
||
{
|
||
int gen, type, zone;
|
||
unsigned long old = 0;
|
||
unsigned long young = 0;
|
||
unsigned long total = 0;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
/* whether this lruvec is completely out of cold folios */
|
||
if (min_seq[!can_swap] + MIN_NR_GENS > max_seq) {
|
||
*nr_to_scan = 0;
|
||
return true;
|
||
}
|
||
|
||
for (type = !can_swap; type < ANON_AND_FILE; type++) {
|
||
unsigned long seq;
|
||
|
||
for (seq = min_seq[type]; seq <= max_seq; seq++) {
|
||
unsigned long size = 0;
|
||
|
||
gen = lru_gen_from_seq(seq);
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++)
|
||
size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
|
||
|
||
total += size;
|
||
if (seq == max_seq)
|
||
young += size;
|
||
else if (seq + MIN_NR_GENS == max_seq)
|
||
old += size;
|
||
}
|
||
}
|
||
|
||
/* try to scrape all its memory if this memcg was deleted */
|
||
if (!mem_cgroup_online(memcg)) {
|
||
*nr_to_scan = total;
|
||
return false;
|
||
}
|
||
|
||
*nr_to_scan = total >> sc->priority;
|
||
|
||
/*
|
||
* The aging tries to be lazy to reduce the overhead, while the eviction
|
||
* stalls when the number of generations reaches MIN_NR_GENS. Hence, the
|
||
* ideal number of generations is MIN_NR_GENS+1.
|
||
*/
|
||
if (min_seq[!can_swap] + MIN_NR_GENS < max_seq)
|
||
return false;
|
||
|
||
/*
|
||
* It's also ideal to spread pages out evenly, i.e., 1/(MIN_NR_GENS+1)
|
||
* of the total number of pages for each generation. A reasonable range
|
||
* for this average portion is [1/MIN_NR_GENS, 1/(MIN_NR_GENS+2)]. The
|
||
* aging cares about the upper bound of hot pages, while the eviction
|
||
* cares about the lower bound of cold pages.
|
||
*/
|
||
if (young * MIN_NR_GENS > total)
|
||
return true;
|
||
if (old * (MIN_NR_GENS + 2) < total)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* For future optimizations:
|
||
* 1. Defer try_to_inc_max_seq() to workqueues to reduce latency for memcg
|
||
* reclaim.
|
||
*/
|
||
static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool can_swap)
|
||
{
|
||
unsigned long nr_to_scan;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
|
||
if (mem_cgroup_below_min(sc->target_mem_cgroup, memcg))
|
||
return -1;
|
||
|
||
if (!should_run_aging(lruvec, max_seq, sc, can_swap, &nr_to_scan))
|
||
return nr_to_scan;
|
||
|
||
/* skip the aging path at the default priority */
|
||
if (sc->priority == DEF_PRIORITY)
|
||
return nr_to_scan;
|
||
|
||
/* skip this lruvec as it's low on cold folios */
|
||
return try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false) ? -1 : 0;
|
||
}
|
||
|
||
static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
int i;
|
||
enum zone_watermarks mark;
|
||
|
||
/* don't abort memcg reclaim to ensure fairness */
|
||
if (!root_reclaim(sc))
|
||
return false;
|
||
|
||
if (sc->nr_reclaimed >= max(sc->nr_to_reclaim, compact_gap(sc->order)))
|
||
return true;
|
||
|
||
/* check the order to exclude compaction-induced reclaim */
|
||
if (!current_is_kswapd() || sc->order)
|
||
return false;
|
||
|
||
mark = sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ?
|
||
WMARK_PROMO : WMARK_HIGH;
|
||
|
||
for (i = 0; i <= sc->reclaim_idx; i++) {
|
||
struct zone *zone = lruvec_pgdat(lruvec)->node_zones + i;
|
||
unsigned long size = wmark_pages(zone, mark) + MIN_LRU_BATCH;
|
||
|
||
if (managed_zone(zone) && !zone_watermark_ok(zone, 0, size, sc->reclaim_idx, 0))
|
||
return false;
|
||
}
|
||
|
||
/* kswapd should abort if all eligible zones are safe */
|
||
return true;
|
||
}
|
||
|
||
static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
long nr_to_scan;
|
||
unsigned long scanned = 0;
|
||
int swappiness = get_swappiness(lruvec, sc);
|
||
|
||
/* clean file folios are more likely to exist */
|
||
if (swappiness && !(sc->gfp_mask & __GFP_IO))
|
||
swappiness = 1;
|
||
|
||
while (true) {
|
||
int delta;
|
||
|
||
nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness);
|
||
if (nr_to_scan <= 0)
|
||
break;
|
||
|
||
delta = evict_folios(lruvec, sc, swappiness);
|
||
if (!delta)
|
||
break;
|
||
|
||
scanned += delta;
|
||
if (scanned >= nr_to_scan)
|
||
break;
|
||
|
||
if (should_abort_scan(lruvec, sc))
|
||
break;
|
||
|
||
cond_resched();
|
||
}
|
||
|
||
/* whether this lruvec should be rotated */
|
||
return nr_to_scan < 0;
|
||
}
|
||
|
||
static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
bool success;
|
||
unsigned long scanned = sc->nr_scanned;
|
||
unsigned long reclaimed = sc->nr_reclaimed;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
|
||
|
||
mem_cgroup_calculate_protection(NULL, memcg);
|
||
|
||
if (mem_cgroup_below_min(NULL, memcg))
|
||
return MEMCG_LRU_YOUNG;
|
||
|
||
if (mem_cgroup_below_low(NULL, memcg)) {
|
||
/* see the comment on MEMCG_NR_GENS */
|
||
if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL)
|
||
return MEMCG_LRU_TAIL;
|
||
|
||
memcg_memory_event(memcg, MEMCG_LOW);
|
||
}
|
||
|
||
success = try_to_shrink_lruvec(lruvec, sc);
|
||
|
||
shrink_slab(sc->gfp_mask, pgdat->node_id, memcg, sc->priority);
|
||
|
||
if (!sc->proactive)
|
||
vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned,
|
||
sc->nr_reclaimed - reclaimed);
|
||
|
||
flush_reclaim_state(sc);
|
||
|
||
if (success && mem_cgroup_online(memcg))
|
||
return MEMCG_LRU_YOUNG;
|
||
|
||
if (!success && lruvec_is_sizable(lruvec, sc))
|
||
return 0;
|
||
|
||
/* one retry if offlined or too small */
|
||
return READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL ?
|
||
MEMCG_LRU_TAIL : MEMCG_LRU_YOUNG;
|
||
}
|
||
|
||
static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
int op;
|
||
int gen;
|
||
int bin;
|
||
int first_bin;
|
||
struct lruvec *lruvec;
|
||
struct lru_gen_folio *lrugen;
|
||
struct mem_cgroup *memcg;
|
||
struct hlist_nulls_node *pos;
|
||
|
||
gen = get_memcg_gen(READ_ONCE(pgdat->memcg_lru.seq));
|
||
bin = first_bin = get_random_u32_below(MEMCG_NR_BINS);
|
||
restart:
|
||
op = 0;
|
||
memcg = NULL;
|
||
|
||
rcu_read_lock();
|
||
|
||
hlist_nulls_for_each_entry_rcu(lrugen, pos, &pgdat->memcg_lru.fifo[gen][bin], list) {
|
||
if (op) {
|
||
lru_gen_rotate_memcg(lruvec, op);
|
||
op = 0;
|
||
}
|
||
|
||
mem_cgroup_put(memcg);
|
||
memcg = NULL;
|
||
|
||
if (gen != READ_ONCE(lrugen->gen))
|
||
continue;
|
||
|
||
lruvec = container_of(lrugen, struct lruvec, lrugen);
|
||
memcg = lruvec_memcg(lruvec);
|
||
|
||
if (!mem_cgroup_tryget(memcg)) {
|
||
lru_gen_release_memcg(memcg);
|
||
memcg = NULL;
|
||
continue;
|
||
}
|
||
|
||
rcu_read_unlock();
|
||
|
||
op = shrink_one(lruvec, sc);
|
||
|
||
rcu_read_lock();
|
||
|
||
if (should_abort_scan(lruvec, sc))
|
||
break;
|
||
}
|
||
|
||
rcu_read_unlock();
|
||
|
||
if (op)
|
||
lru_gen_rotate_memcg(lruvec, op);
|
||
|
||
mem_cgroup_put(memcg);
|
||
|
||
if (!is_a_nulls(pos))
|
||
return;
|
||
|
||
/* restart if raced with lru_gen_rotate_memcg() */
|
||
if (gen != get_nulls_value(pos))
|
||
goto restart;
|
||
|
||
/* try the rest of the bins of the current generation */
|
||
bin = get_memcg_bin(bin + 1);
|
||
if (bin != first_bin)
|
||
goto restart;
|
||
}
|
||
|
||
static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
struct blk_plug plug;
|
||
|
||
VM_WARN_ON_ONCE(root_reclaim(sc));
|
||
VM_WARN_ON_ONCE(!sc->may_writepage || !sc->may_unmap);
|
||
|
||
lru_add_drain();
|
||
|
||
blk_start_plug(&plug);
|
||
|
||
set_mm_walk(NULL, sc->proactive);
|
||
|
||
if (try_to_shrink_lruvec(lruvec, sc))
|
||
lru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG);
|
||
|
||
clear_mm_walk();
|
||
|
||
blk_finish_plug(&plug);
|
||
}
|
||
|
||
static void set_initial_priority(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
int priority;
|
||
unsigned long reclaimable;
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(NULL, pgdat);
|
||
|
||
if (sc->priority != DEF_PRIORITY || sc->nr_to_reclaim < MIN_LRU_BATCH)
|
||
return;
|
||
/*
|
||
* Determine the initial priority based on
|
||
* (total >> priority) * reclaimed_to_scanned_ratio = nr_to_reclaim,
|
||
* where reclaimed_to_scanned_ratio = inactive / total.
|
||
*/
|
||
reclaimable = node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
if (get_swappiness(lruvec, sc))
|
||
reclaimable += node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
|
||
/* round down reclaimable and round up sc->nr_to_reclaim */
|
||
priority = fls_long(reclaimable) - 1 - fls_long(sc->nr_to_reclaim - 1);
|
||
|
||
sc->priority = clamp(priority, 0, DEF_PRIORITY);
|
||
}
|
||
|
||
static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
struct blk_plug plug;
|
||
unsigned long reclaimed = sc->nr_reclaimed;
|
||
|
||
VM_WARN_ON_ONCE(!root_reclaim(sc));
|
||
|
||
/*
|
||
* Unmapped clean folios are already prioritized. Scanning for more of
|
||
* them is likely futile and can cause high reclaim latency when there
|
||
* is a large number of memcgs.
|
||
*/
|
||
if (!sc->may_writepage || !sc->may_unmap)
|
||
goto done;
|
||
|
||
lru_add_drain();
|
||
|
||
blk_start_plug(&plug);
|
||
|
||
set_mm_walk(pgdat, sc->proactive);
|
||
|
||
set_initial_priority(pgdat, sc);
|
||
|
||
if (current_is_kswapd())
|
||
sc->nr_reclaimed = 0;
|
||
|
||
if (mem_cgroup_disabled())
|
||
shrink_one(&pgdat->__lruvec, sc);
|
||
else
|
||
shrink_many(pgdat, sc);
|
||
|
||
if (current_is_kswapd())
|
||
sc->nr_reclaimed += reclaimed;
|
||
|
||
clear_mm_walk();
|
||
|
||
blk_finish_plug(&plug);
|
||
done:
|
||
/* kswapd should never fail */
|
||
pgdat->kswapd_failures = 0;
|
||
}
|
||
|
||
/******************************************************************************
|
||
* state change
|
||
******************************************************************************/
|
||
|
||
static bool __maybe_unused state_is_valid(struct lruvec *lruvec)
|
||
{
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
|
||
if (lrugen->enabled) {
|
||
enum lru_list lru;
|
||
|
||
for_each_evictable_lru(lru) {
|
||
if (!list_empty(&lruvec->lists[lru]))
|
||
return false;
|
||
}
|
||
} else {
|
||
int gen, type, zone;
|
||
|
||
for_each_gen_type_zone(gen, type, zone) {
|
||
if (!list_empty(&lrugen->folios[gen][type][zone]))
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool fill_evictable(struct lruvec *lruvec)
|
||
{
|
||
enum lru_list lru;
|
||
int remaining = MAX_LRU_BATCH;
|
||
|
||
for_each_evictable_lru(lru) {
|
||
int type = is_file_lru(lru);
|
||
bool active = is_active_lru(lru);
|
||
struct list_head *head = &lruvec->lists[lru];
|
||
|
||
while (!list_empty(head)) {
|
||
bool success;
|
||
struct folio *folio = lru_to_folio(head);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio) != active, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_lru_gen(folio) != -1, folio);
|
||
|
||
lruvec_del_folio(lruvec, folio);
|
||
success = lru_gen_add_folio(lruvec, folio, false);
|
||
VM_WARN_ON_ONCE(!success);
|
||
|
||
if (!--remaining)
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static bool drain_evictable(struct lruvec *lruvec)
|
||
{
|
||
int gen, type, zone;
|
||
int remaining = MAX_LRU_BATCH;
|
||
|
||
for_each_gen_type_zone(gen, type, zone) {
|
||
struct list_head *head = &lruvec->lrugen.folios[gen][type][zone];
|
||
|
||
while (!list_empty(head)) {
|
||
bool success;
|
||
struct folio *folio = lru_to_folio(head);
|
||
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio);
|
||
VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio);
|
||
|
||
success = lru_gen_del_folio(lruvec, folio, false);
|
||
VM_WARN_ON_ONCE(!success);
|
||
lruvec_add_folio(lruvec, folio);
|
||
|
||
if (!--remaining)
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
static void lru_gen_change_state(bool enabled)
|
||
{
|
||
static DEFINE_MUTEX(state_mutex);
|
||
|
||
struct mem_cgroup *memcg;
|
||
|
||
cgroup_lock();
|
||
cpus_read_lock();
|
||
get_online_mems();
|
||
mutex_lock(&state_mutex);
|
||
|
||
if (enabled == lru_gen_enabled())
|
||
goto unlock;
|
||
|
||
if (enabled)
|
||
static_branch_enable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]);
|
||
else
|
||
static_branch_disable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]);
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
int nid;
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
|
||
VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
|
||
VM_WARN_ON_ONCE(!state_is_valid(lruvec));
|
||
|
||
lruvec->lrugen.enabled = enabled;
|
||
|
||
while (!(enabled ? fill_evictable(lruvec) : drain_evictable(lruvec))) {
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
cond_resched();
|
||
spin_lock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
spin_unlock_irq(&lruvec->lru_lock);
|
||
}
|
||
|
||
cond_resched();
|
||
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
|
||
unlock:
|
||
mutex_unlock(&state_mutex);
|
||
put_online_mems();
|
||
cpus_read_unlock();
|
||
cgroup_unlock();
|
||
}
|
||
|
||
/******************************************************************************
|
||
* sysfs interface
|
||
******************************************************************************/
|
||
|
||
static ssize_t min_ttl_ms_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
|
||
{
|
||
return sysfs_emit(buf, "%u\n", jiffies_to_msecs(READ_ONCE(lru_gen_min_ttl)));
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static ssize_t min_ttl_ms_store(struct kobject *kobj, struct kobj_attribute *attr,
|
||
const char *buf, size_t len)
|
||
{
|
||
unsigned int msecs;
|
||
|
||
if (kstrtouint(buf, 0, &msecs))
|
||
return -EINVAL;
|
||
|
||
WRITE_ONCE(lru_gen_min_ttl, msecs_to_jiffies(msecs));
|
||
|
||
return len;
|
||
}
|
||
|
||
static struct kobj_attribute lru_gen_min_ttl_attr = __ATTR_RW(min_ttl_ms);
|
||
|
||
static ssize_t enabled_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
|
||
{
|
||
unsigned int caps = 0;
|
||
|
||
if (get_cap(LRU_GEN_CORE))
|
||
caps |= BIT(LRU_GEN_CORE);
|
||
|
||
if (should_walk_mmu())
|
||
caps |= BIT(LRU_GEN_MM_WALK);
|
||
|
||
if (should_clear_pmd_young())
|
||
caps |= BIT(LRU_GEN_NONLEAF_YOUNG);
|
||
|
||
return sysfs_emit(buf, "0x%04x\n", caps);
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
|
||
const char *buf, size_t len)
|
||
{
|
||
int i;
|
||
unsigned int caps;
|
||
|
||
if (tolower(*buf) == 'n')
|
||
caps = 0;
|
||
else if (tolower(*buf) == 'y')
|
||
caps = -1;
|
||
else if (kstrtouint(buf, 0, &caps))
|
||
return -EINVAL;
|
||
|
||
for (i = 0; i < NR_LRU_GEN_CAPS; i++) {
|
||
bool enabled = caps & BIT(i);
|
||
|
||
if (i == LRU_GEN_CORE)
|
||
lru_gen_change_state(enabled);
|
||
else if (enabled)
|
||
static_branch_enable(&lru_gen_caps[i]);
|
||
else
|
||
static_branch_disable(&lru_gen_caps[i]);
|
||
}
|
||
|
||
return len;
|
||
}
|
||
|
||
static struct kobj_attribute lru_gen_enabled_attr = __ATTR_RW(enabled);
|
||
|
||
static struct attribute *lru_gen_attrs[] = {
|
||
&lru_gen_min_ttl_attr.attr,
|
||
&lru_gen_enabled_attr.attr,
|
||
NULL
|
||
};
|
||
|
||
static const struct attribute_group lru_gen_attr_group = {
|
||
.name = "lru_gen",
|
||
.attrs = lru_gen_attrs,
|
||
};
|
||
|
||
/******************************************************************************
|
||
* debugfs interface
|
||
******************************************************************************/
|
||
|
||
static void *lru_gen_seq_start(struct seq_file *m, loff_t *pos)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
loff_t nr_to_skip = *pos;
|
||
|
||
m->private = kvmalloc(PATH_MAX, GFP_KERNEL);
|
||
if (!m->private)
|
||
return ERR_PTR(-ENOMEM);
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
int nid;
|
||
|
||
for_each_node_state(nid, N_MEMORY) {
|
||
if (!nr_to_skip--)
|
||
return get_lruvec(memcg, nid);
|
||
}
|
||
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
|
||
|
||
return NULL;
|
||
}
|
||
|
||
static void lru_gen_seq_stop(struct seq_file *m, void *v)
|
||
{
|
||
if (!IS_ERR_OR_NULL(v))
|
||
mem_cgroup_iter_break(NULL, lruvec_memcg(v));
|
||
|
||
kvfree(m->private);
|
||
m->private = NULL;
|
||
}
|
||
|
||
static void *lru_gen_seq_next(struct seq_file *m, void *v, loff_t *pos)
|
||
{
|
||
int nid = lruvec_pgdat(v)->node_id;
|
||
struct mem_cgroup *memcg = lruvec_memcg(v);
|
||
|
||
++*pos;
|
||
|
||
nid = next_memory_node(nid);
|
||
if (nid == MAX_NUMNODES) {
|
||
memcg = mem_cgroup_iter(NULL, memcg, NULL);
|
||
if (!memcg)
|
||
return NULL;
|
||
|
||
nid = first_memory_node;
|
||
}
|
||
|
||
return get_lruvec(memcg, nid);
|
||
}
|
||
|
||
static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
|
||
unsigned long max_seq, unsigned long *min_seq,
|
||
unsigned long seq)
|
||
{
|
||
int i;
|
||
int type, tier;
|
||
int hist = lru_hist_from_seq(seq);
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
for (tier = 0; tier < MAX_NR_TIERS; tier++) {
|
||
seq_printf(m, " %10d", tier);
|
||
for (type = 0; type < ANON_AND_FILE; type++) {
|
||
const char *s = " ";
|
||
unsigned long n[3] = {};
|
||
|
||
if (seq == max_seq) {
|
||
s = "RT ";
|
||
n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]);
|
||
n[1] = READ_ONCE(lrugen->avg_total[type][tier]);
|
||
} else if (seq == min_seq[type] || NR_HIST_GENS > 1) {
|
||
s = "rep";
|
||
n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]);
|
||
n[1] = atomic_long_read(&lrugen->evicted[hist][type][tier]);
|
||
if (tier)
|
||
n[2] = READ_ONCE(lrugen->protected[hist][type][tier - 1]);
|
||
}
|
||
|
||
for (i = 0; i < 3; i++)
|
||
seq_printf(m, " %10lu%c", n[i], s[i]);
|
||
}
|
||
seq_putc(m, '\n');
|
||
}
|
||
|
||
if (!mm_state)
|
||
return;
|
||
|
||
seq_puts(m, " ");
|
||
for (i = 0; i < NR_MM_STATS; i++) {
|
||
const char *s = " ";
|
||
unsigned long n = 0;
|
||
|
||
if (seq == max_seq && NR_HIST_GENS == 1) {
|
||
s = "LOYNFA";
|
||
n = READ_ONCE(mm_state->stats[hist][i]);
|
||
} else if (seq != max_seq && NR_HIST_GENS > 1) {
|
||
s = "loynfa";
|
||
n = READ_ONCE(mm_state->stats[hist][i]);
|
||
}
|
||
|
||
seq_printf(m, " %10lu%c", n, s[i]);
|
||
}
|
||
seq_putc(m, '\n');
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static int lru_gen_seq_show(struct seq_file *m, void *v)
|
||
{
|
||
unsigned long seq;
|
||
bool full = !debugfs_real_fops(m->file)->write;
|
||
struct lruvec *lruvec = v;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
int nid = lruvec_pgdat(lruvec)->node_id;
|
||
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (nid == first_memory_node) {
|
||
const char *path = memcg ? m->private : "";
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
if (memcg)
|
||
cgroup_path(memcg->css.cgroup, m->private, PATH_MAX);
|
||
#endif
|
||
seq_printf(m, "memcg %5hu %s\n", mem_cgroup_id(memcg), path);
|
||
}
|
||
|
||
seq_printf(m, " node %5d\n", nid);
|
||
|
||
if (!full)
|
||
seq = min_seq[LRU_GEN_ANON];
|
||
else if (max_seq >= MAX_NR_GENS)
|
||
seq = max_seq - MAX_NR_GENS + 1;
|
||
else
|
||
seq = 0;
|
||
|
||
for (; seq <= max_seq; seq++) {
|
||
int type, zone;
|
||
int gen = lru_gen_from_seq(seq);
|
||
unsigned long birth = READ_ONCE(lruvec->lrugen.timestamps[gen]);
|
||
|
||
seq_printf(m, " %10lu %10u", seq, jiffies_to_msecs(jiffies - birth));
|
||
|
||
for (type = 0; type < ANON_AND_FILE; type++) {
|
||
unsigned long size = 0;
|
||
char mark = full && seq < min_seq[type] ? 'x' : ' ';
|
||
|
||
for (zone = 0; zone < MAX_NR_ZONES; zone++)
|
||
size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L);
|
||
|
||
seq_printf(m, " %10lu%c", size, mark);
|
||
}
|
||
|
||
seq_putc(m, '\n');
|
||
|
||
if (full)
|
||
lru_gen_seq_show_full(m, lruvec, max_seq, min_seq, seq);
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static const struct seq_operations lru_gen_seq_ops = {
|
||
.start = lru_gen_seq_start,
|
||
.stop = lru_gen_seq_stop,
|
||
.next = lru_gen_seq_next,
|
||
.show = lru_gen_seq_show,
|
||
};
|
||
|
||
static int run_aging(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,
|
||
bool can_swap, bool force_scan)
|
||
{
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (seq < max_seq)
|
||
return 0;
|
||
|
||
if (seq > max_seq)
|
||
return -EINVAL;
|
||
|
||
if (!force_scan && min_seq[!can_swap] + MAX_NR_GENS - 1 <= max_seq)
|
||
return -ERANGE;
|
||
|
||
try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, force_scan);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int run_eviction(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,
|
||
int swappiness, unsigned long nr_to_reclaim)
|
||
{
|
||
DEFINE_MAX_SEQ(lruvec);
|
||
|
||
if (seq + MIN_NR_GENS > max_seq)
|
||
return -EINVAL;
|
||
|
||
sc->nr_reclaimed = 0;
|
||
|
||
while (!signal_pending(current)) {
|
||
DEFINE_MIN_SEQ(lruvec);
|
||
|
||
if (seq < min_seq[!swappiness])
|
||
return 0;
|
||
|
||
if (sc->nr_reclaimed >= nr_to_reclaim)
|
||
return 0;
|
||
|
||
if (!evict_folios(lruvec, sc, swappiness))
|
||
return 0;
|
||
|
||
cond_resched();
|
||
}
|
||
|
||
return -EINTR;
|
||
}
|
||
|
||
static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq,
|
||
struct scan_control *sc, int swappiness, unsigned long opt)
|
||
{
|
||
struct lruvec *lruvec;
|
||
int err = -EINVAL;
|
||
struct mem_cgroup *memcg = NULL;
|
||
|
||
if (nid < 0 || nid >= MAX_NUMNODES || !node_state(nid, N_MEMORY))
|
||
return -EINVAL;
|
||
|
||
if (!mem_cgroup_disabled()) {
|
||
rcu_read_lock();
|
||
|
||
memcg = mem_cgroup_from_id(memcg_id);
|
||
if (!mem_cgroup_tryget(memcg))
|
||
memcg = NULL;
|
||
|
||
rcu_read_unlock();
|
||
|
||
if (!memcg)
|
||
return -EINVAL;
|
||
}
|
||
|
||
if (memcg_id != mem_cgroup_id(memcg))
|
||
goto done;
|
||
|
||
lruvec = get_lruvec(memcg, nid);
|
||
|
||
if (swappiness < 0)
|
||
swappiness = get_swappiness(lruvec, sc);
|
||
else if (swappiness > 200)
|
||
goto done;
|
||
|
||
switch (cmd) {
|
||
case '+':
|
||
err = run_aging(lruvec, seq, sc, swappiness, opt);
|
||
break;
|
||
case '-':
|
||
err = run_eviction(lruvec, seq, sc, swappiness, opt);
|
||
break;
|
||
}
|
||
done:
|
||
mem_cgroup_put(memcg);
|
||
|
||
return err;
|
||
}
|
||
|
||
/* see Documentation/admin-guide/mm/multigen_lru.rst for details */
|
||
static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
|
||
size_t len, loff_t *pos)
|
||
{
|
||
void *buf;
|
||
char *cur, *next;
|
||
unsigned int flags;
|
||
struct blk_plug plug;
|
||
int err = -EINVAL;
|
||
struct scan_control sc = {
|
||
.may_writepage = true,
|
||
.may_unmap = true,
|
||
.may_swap = true,
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.gfp_mask = GFP_KERNEL,
|
||
};
|
||
|
||
buf = kvmalloc(len + 1, GFP_KERNEL);
|
||
if (!buf)
|
||
return -ENOMEM;
|
||
|
||
if (copy_from_user(buf, src, len)) {
|
||
kvfree(buf);
|
||
return -EFAULT;
|
||
}
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
flags = memalloc_noreclaim_save();
|
||
blk_start_plug(&plug);
|
||
if (!set_mm_walk(NULL, true)) {
|
||
err = -ENOMEM;
|
||
goto done;
|
||
}
|
||
|
||
next = buf;
|
||
next[len] = '\0';
|
||
|
||
while ((cur = strsep(&next, ",;\n"))) {
|
||
int n;
|
||
int end;
|
||
char cmd;
|
||
unsigned int memcg_id;
|
||
unsigned int nid;
|
||
unsigned long seq;
|
||
unsigned int swappiness = -1;
|
||
unsigned long opt = -1;
|
||
|
||
cur = skip_spaces(cur);
|
||
if (!*cur)
|
||
continue;
|
||
|
||
n = sscanf(cur, "%c %u %u %lu %n %u %n %lu %n", &cmd, &memcg_id, &nid,
|
||
&seq, &end, &swappiness, &end, &opt, &end);
|
||
if (n < 4 || cur[end]) {
|
||
err = -EINVAL;
|
||
break;
|
||
}
|
||
|
||
err = run_cmd(cmd, memcg_id, nid, seq, &sc, swappiness, opt);
|
||
if (err)
|
||
break;
|
||
}
|
||
done:
|
||
clear_mm_walk();
|
||
blk_finish_plug(&plug);
|
||
memalloc_noreclaim_restore(flags);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
kvfree(buf);
|
||
|
||
return err ? : len;
|
||
}
|
||
|
||
static int lru_gen_seq_open(struct inode *inode, struct file *file)
|
||
{
|
||
return seq_open(file, &lru_gen_seq_ops);
|
||
}
|
||
|
||
static const struct file_operations lru_gen_rw_fops = {
|
||
.open = lru_gen_seq_open,
|
||
.read = seq_read,
|
||
.write = lru_gen_seq_write,
|
||
.llseek = seq_lseek,
|
||
.release = seq_release,
|
||
};
|
||
|
||
static const struct file_operations lru_gen_ro_fops = {
|
||
.open = lru_gen_seq_open,
|
||
.read = seq_read,
|
||
.llseek = seq_lseek,
|
||
.release = seq_release,
|
||
};
|
||
|
||
/******************************************************************************
|
||
* initialization
|
||
******************************************************************************/
|
||
|
||
void lru_gen_init_pgdat(struct pglist_data *pgdat)
|
||
{
|
||
int i, j;
|
||
|
||
spin_lock_init(&pgdat->memcg_lru.lock);
|
||
|
||
for (i = 0; i < MEMCG_NR_GENS; i++) {
|
||
for (j = 0; j < MEMCG_NR_BINS; j++)
|
||
INIT_HLIST_NULLS_HEAD(&pgdat->memcg_lru.fifo[i][j], i);
|
||
}
|
||
}
|
||
|
||
void lru_gen_init_lruvec(struct lruvec *lruvec)
|
||
{
|
||
int i;
|
||
int gen, type, zone;
|
||
struct lru_gen_folio *lrugen = &lruvec->lrugen;
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
lrugen->max_seq = MIN_NR_GENS + 1;
|
||
lrugen->enabled = lru_gen_enabled();
|
||
|
||
for (i = 0; i <= MIN_NR_GENS + 1; i++)
|
||
lrugen->timestamps[i] = jiffies;
|
||
|
||
for_each_gen_type_zone(gen, type, zone)
|
||
INIT_LIST_HEAD(&lrugen->folios[gen][type][zone]);
|
||
|
||
if (mm_state)
|
||
mm_state->seq = MIN_NR_GENS;
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
|
||
void lru_gen_init_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
|
||
if (!mm_list)
|
||
return;
|
||
|
||
INIT_LIST_HEAD(&mm_list->fifo);
|
||
spin_lock_init(&mm_list->lock);
|
||
}
|
||
|
||
void lru_gen_exit_memcg(struct mem_cgroup *memcg)
|
||
{
|
||
int i;
|
||
int nid;
|
||
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
|
||
|
||
VM_WARN_ON_ONCE(mm_list && !list_empty(&mm_list->fifo));
|
||
|
||
for_each_node(nid) {
|
||
struct lruvec *lruvec = get_lruvec(memcg, nid);
|
||
struct lru_gen_mm_state *mm_state = get_mm_state(lruvec);
|
||
|
||
VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
|
||
sizeof(lruvec->lrugen.nr_pages)));
|
||
|
||
lruvec->lrugen.list.next = LIST_POISON1;
|
||
|
||
if (!mm_state)
|
||
continue;
|
||
|
||
for (i = 0; i < NR_BLOOM_FILTERS; i++) {
|
||
bitmap_free(mm_state->filters[i]);
|
||
mm_state->filters[i] = NULL;
|
||
}
|
||
}
|
||
}
|
||
|
||
#endif /* CONFIG_MEMCG */
|
||
|
||
static int __init init_lru_gen(void)
|
||
{
|
||
BUILD_BUG_ON(MIN_NR_GENS + 1 >= MAX_NR_GENS);
|
||
BUILD_BUG_ON(BIT(LRU_GEN_WIDTH) <= MAX_NR_GENS);
|
||
|
||
if (sysfs_create_group(mm_kobj, &lru_gen_attr_group))
|
||
pr_err("lru_gen: failed to create sysfs group\n");
|
||
|
||
debugfs_create_file("lru_gen", 0644, NULL, NULL, &lru_gen_rw_fops);
|
||
debugfs_create_file("lru_gen_full", 0444, NULL, NULL, &lru_gen_ro_fops);
|
||
|
||
return 0;
|
||
};
|
||
late_initcall(init_lru_gen);
|
||
|
||
#else /* !CONFIG_LRU_GEN */
|
||
|
||
static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
BUILD_BUG();
|
||
}
|
||
|
||
static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
BUILD_BUG();
|
||
}
|
||
|
||
static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
BUILD_BUG();
|
||
}
|
||
|
||
#endif /* CONFIG_LRU_GEN */
|
||
|
||
static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
|
||
{
|
||
unsigned long nr[NR_LRU_LISTS];
|
||
unsigned long targets[NR_LRU_LISTS];
|
||
unsigned long nr_to_scan;
|
||
enum lru_list lru;
|
||
unsigned long nr_reclaimed = 0;
|
||
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
|
||
bool proportional_reclaim;
|
||
struct blk_plug plug;
|
||
|
||
if (lru_gen_enabled() && !root_reclaim(sc)) {
|
||
lru_gen_shrink_lruvec(lruvec, sc);
|
||
return;
|
||
}
|
||
|
||
get_scan_count(lruvec, sc, nr);
|
||
|
||
/* Record the original scan target for proportional adjustments later */
|
||
memcpy(targets, nr, sizeof(nr));
|
||
|
||
/*
|
||
* Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
|
||
* event that can occur when there is little memory pressure e.g.
|
||
* multiple streaming readers/writers. Hence, we do not abort scanning
|
||
* when the requested number of pages are reclaimed when scanning at
|
||
* DEF_PRIORITY on the assumption that the fact we are direct
|
||
* reclaiming implies that kswapd is not keeping up and it is best to
|
||
* do a batch of work at once. For memcg reclaim one check is made to
|
||
* abort proportional reclaim if either the file or anon lru has already
|
||
* dropped to zero at the first pass.
|
||
*/
|
||
proportional_reclaim = (!cgroup_reclaim(sc) && !current_is_kswapd() &&
|
||
sc->priority == DEF_PRIORITY);
|
||
|
||
blk_start_plug(&plug);
|
||
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
|
||
nr[LRU_INACTIVE_FILE]) {
|
||
unsigned long nr_anon, nr_file, percentage;
|
||
unsigned long nr_scanned;
|
||
|
||
for_each_evictable_lru(lru) {
|
||
if (nr[lru]) {
|
||
nr_to_scan = min(nr[lru], SWAP_CLUSTER_MAX);
|
||
nr[lru] -= nr_to_scan;
|
||
|
||
nr_reclaimed += shrink_list(lru, nr_to_scan,
|
||
lruvec, sc);
|
||
}
|
||
}
|
||
|
||
cond_resched();
|
||
|
||
if (nr_reclaimed < nr_to_reclaim || proportional_reclaim)
|
||
continue;
|
||
|
||
/*
|
||
* For kswapd and memcg, reclaim at least the number of pages
|
||
* requested. Ensure that the anon and file LRUs are scanned
|
||
* proportionally what was requested by get_scan_count(). We
|
||
* stop reclaiming one LRU and reduce the amount scanning
|
||
* proportional to the original scan target.
|
||
*/
|
||
nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE];
|
||
nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON];
|
||
|
||
/*
|
||
* It's just vindictive to attack the larger once the smaller
|
||
* has gone to zero. And given the way we stop scanning the
|
||
* smaller below, this makes sure that we only make one nudge
|
||
* towards proportionality once we've got nr_to_reclaim.
|
||
*/
|
||
if (!nr_file || !nr_anon)
|
||
break;
|
||
|
||
if (nr_file > nr_anon) {
|
||
unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
|
||
targets[LRU_ACTIVE_ANON] + 1;
|
||
lru = LRU_BASE;
|
||
percentage = nr_anon * 100 / scan_target;
|
||
} else {
|
||
unsigned long scan_target = targets[LRU_INACTIVE_FILE] +
|
||
targets[LRU_ACTIVE_FILE] + 1;
|
||
lru = LRU_FILE;
|
||
percentage = nr_file * 100 / scan_target;
|
||
}
|
||
|
||
/* Stop scanning the smaller of the LRU */
|
||
nr[lru] = 0;
|
||
nr[lru + LRU_ACTIVE] = 0;
|
||
|
||
/*
|
||
* Recalculate the other LRU scan count based on its original
|
||
* scan target and the percentage scanning already complete
|
||
*/
|
||
lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE;
|
||
nr_scanned = targets[lru] - nr[lru];
|
||
nr[lru] = targets[lru] * (100 - percentage) / 100;
|
||
nr[lru] -= min(nr[lru], nr_scanned);
|
||
|
||
lru += LRU_ACTIVE;
|
||
nr_scanned = targets[lru] - nr[lru];
|
||
nr[lru] = targets[lru] * (100 - percentage) / 100;
|
||
nr[lru] -= min(nr[lru], nr_scanned);
|
||
}
|
||
blk_finish_plug(&plug);
|
||
sc->nr_reclaimed += nr_reclaimed;
|
||
|
||
/*
|
||
* Even if we did not try to evict anon pages at all, we want to
|
||
* rebalance the anon lru active/inactive ratio.
|
||
*/
|
||
if (can_age_anon_pages(lruvec_pgdat(lruvec), sc) &&
|
||
inactive_is_low(lruvec, LRU_INACTIVE_ANON))
|
||
shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
|
||
sc, LRU_ACTIVE_ANON);
|
||
}
|
||
|
||
/* Use reclaim/compaction for costly allocs or under memory pressure */
|
||
static bool in_reclaim_compaction(struct scan_control *sc)
|
||
{
|
||
if (gfp_compaction_allowed(sc->gfp_mask) && sc->order &&
|
||
(sc->order > PAGE_ALLOC_COSTLY_ORDER ||
|
||
sc->priority < DEF_PRIORITY - 2))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* Reclaim/compaction is used for high-order allocation requests. It reclaims
|
||
* order-0 pages before compacting the zone. should_continue_reclaim() returns
|
||
* true if more pages should be reclaimed such that when the page allocator
|
||
* calls try_to_compact_pages() that it will have enough free pages to succeed.
|
||
* It will give up earlier than that if there is difficulty reclaiming pages.
|
||
*/
|
||
static inline bool should_continue_reclaim(struct pglist_data *pgdat,
|
||
unsigned long nr_reclaimed,
|
||
struct scan_control *sc)
|
||
{
|
||
unsigned long pages_for_compaction;
|
||
unsigned long inactive_lru_pages;
|
||
int z;
|
||
|
||
/* If not in reclaim/compaction mode, stop */
|
||
if (!in_reclaim_compaction(sc))
|
||
return false;
|
||
|
||
/*
|
||
* Stop if we failed to reclaim any pages from the last SWAP_CLUSTER_MAX
|
||
* number of pages that were scanned. This will return to the caller
|
||
* with the risk reclaim/compaction and the resulting allocation attempt
|
||
* fails. In the past we have tried harder for __GFP_RETRY_MAYFAIL
|
||
* allocations through requiring that the full LRU list has been scanned
|
||
* first, by assuming that zero delta of sc->nr_scanned means full LRU
|
||
* scan, but that approximation was wrong, and there were corner cases
|
||
* where always a non-zero amount of pages were scanned.
|
||
*/
|
||
if (!nr_reclaimed)
|
||
return false;
|
||
|
||
/* If compaction would go ahead or the allocation would succeed, stop */
|
||
for (z = 0; z <= sc->reclaim_idx; z++) {
|
||
struct zone *zone = &pgdat->node_zones[z];
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
/* Allocation can already succeed, nothing to do */
|
||
if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone),
|
||
sc->reclaim_idx, 0))
|
||
return false;
|
||
|
||
if (compaction_suitable(zone, sc->order, sc->reclaim_idx))
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* If we have not reclaimed enough pages for compaction and the
|
||
* inactive lists are large enough, continue reclaiming
|
||
*/
|
||
pages_for_compaction = compact_gap(sc->order);
|
||
inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);
|
||
if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))
|
||
inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);
|
||
|
||
return inactive_lru_pages > pages_for_compaction;
|
||
}
|
||
|
||
static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *target_memcg = sc->target_mem_cgroup;
|
||
struct mem_cgroup *memcg;
|
||
|
||
memcg = mem_cgroup_iter(target_memcg, NULL, NULL);
|
||
do {
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
unsigned long reclaimed;
|
||
unsigned long scanned;
|
||
|
||
/*
|
||
* This loop can become CPU-bound when target memcgs
|
||
* aren't eligible for reclaim - either because they
|
||
* don't have any reclaimable pages, or because their
|
||
* memory is explicitly protected. Avoid soft lockups.
|
||
*/
|
||
cond_resched();
|
||
|
||
mem_cgroup_calculate_protection(target_memcg, memcg);
|
||
|
||
if (mem_cgroup_below_min(target_memcg, memcg)) {
|
||
/*
|
||
* Hard protection.
|
||
* If there is no reclaimable memory, OOM.
|
||
*/
|
||
continue;
|
||
} else if (mem_cgroup_below_low(target_memcg, memcg)) {
|
||
/*
|
||
* Soft protection.
|
||
* Respect the protection only as long as
|
||
* there is an unprotected supply
|
||
* of reclaimable memory from other cgroups.
|
||
*/
|
||
if (!sc->memcg_low_reclaim) {
|
||
sc->memcg_low_skipped = 1;
|
||
continue;
|
||
}
|
||
memcg_memory_event(memcg, MEMCG_LOW);
|
||
}
|
||
|
||
reclaimed = sc->nr_reclaimed;
|
||
scanned = sc->nr_scanned;
|
||
|
||
shrink_lruvec(lruvec, sc);
|
||
|
||
shrink_slab(sc->gfp_mask, pgdat->node_id, memcg,
|
||
sc->priority);
|
||
|
||
/* Record the group's reclaim efficiency */
|
||
if (!sc->proactive)
|
||
vmpressure(sc->gfp_mask, memcg, false,
|
||
sc->nr_scanned - scanned,
|
||
sc->nr_reclaimed - reclaimed);
|
||
|
||
} while ((memcg = mem_cgroup_iter(target_memcg, memcg, NULL)));
|
||
}
|
||
|
||
static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
unsigned long nr_reclaimed, nr_scanned, nr_node_reclaimed;
|
||
struct lruvec *target_lruvec;
|
||
bool reclaimable = false;
|
||
|
||
if (lru_gen_enabled() && root_reclaim(sc)) {
|
||
lru_gen_shrink_node(pgdat, sc);
|
||
return;
|
||
}
|
||
|
||
target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat);
|
||
|
||
again:
|
||
memset(&sc->nr, 0, sizeof(sc->nr));
|
||
|
||
nr_reclaimed = sc->nr_reclaimed;
|
||
nr_scanned = sc->nr_scanned;
|
||
|
||
prepare_scan_control(pgdat, sc);
|
||
|
||
shrink_node_memcgs(pgdat, sc);
|
||
|
||
flush_reclaim_state(sc);
|
||
|
||
nr_node_reclaimed = sc->nr_reclaimed - nr_reclaimed;
|
||
|
||
/* Record the subtree's reclaim efficiency */
|
||
if (!sc->proactive)
|
||
vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
|
||
sc->nr_scanned - nr_scanned, nr_node_reclaimed);
|
||
|
||
if (nr_node_reclaimed)
|
||
reclaimable = true;
|
||
|
||
if (current_is_kswapd()) {
|
||
/*
|
||
* If reclaim is isolating dirty pages under writeback,
|
||
* it implies that the long-lived page allocation rate
|
||
* is exceeding the page laundering rate. Either the
|
||
* global limits are not being effective at throttling
|
||
* processes due to the page distribution throughout
|
||
* zones or there is heavy usage of a slow backing
|
||
* device. The only option is to throttle from reclaim
|
||
* context which is not ideal as there is no guarantee
|
||
* the dirtying process is throttled in the same way
|
||
* balance_dirty_pages() manages.
|
||
*
|
||
* Once a node is flagged PGDAT_WRITEBACK, kswapd will
|
||
* count the number of pages under pages flagged for
|
||
* immediate reclaim and stall if any are encountered
|
||
* in the nr_immediate check below.
|
||
*/
|
||
if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken)
|
||
set_bit(PGDAT_WRITEBACK, &pgdat->flags);
|
||
|
||
/* Allow kswapd to start writing pages during reclaim.*/
|
||
if (sc->nr.unqueued_dirty == sc->nr.file_taken)
|
||
set_bit(PGDAT_DIRTY, &pgdat->flags);
|
||
|
||
/*
|
||
* If kswapd scans pages marked for immediate
|
||
* reclaim and under writeback (nr_immediate), it
|
||
* implies that pages are cycling through the LRU
|
||
* faster than they are written so forcibly stall
|
||
* until some pages complete writeback.
|
||
*/
|
||
if (sc->nr.immediate)
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK);
|
||
}
|
||
|
||
/*
|
||
* Tag a node/memcg as congested if all the dirty pages were marked
|
||
* for writeback and immediate reclaim (counted in nr.congested).
|
||
*
|
||
* Legacy memcg will stall in page writeback so avoid forcibly
|
||
* stalling in reclaim_throttle().
|
||
*/
|
||
if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) {
|
||
if (cgroup_reclaim(sc) && writeback_throttling_sane(sc))
|
||
set_bit(LRUVEC_CGROUP_CONGESTED, &target_lruvec->flags);
|
||
|
||
if (current_is_kswapd())
|
||
set_bit(LRUVEC_NODE_CONGESTED, &target_lruvec->flags);
|
||
}
|
||
|
||
/*
|
||
* Stall direct reclaim for IO completions if the lruvec is
|
||
* node is congested. Allow kswapd to continue until it
|
||
* starts encountering unqueued dirty pages or cycling through
|
||
* the LRU too quickly.
|
||
*/
|
||
if (!current_is_kswapd() && current_may_throttle() &&
|
||
!sc->hibernation_mode &&
|
||
(test_bit(LRUVEC_CGROUP_CONGESTED, &target_lruvec->flags) ||
|
||
test_bit(LRUVEC_NODE_CONGESTED, &target_lruvec->flags)))
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_CONGESTED);
|
||
|
||
if (should_continue_reclaim(pgdat, nr_node_reclaimed, sc))
|
||
goto again;
|
||
|
||
/*
|
||
* Kswapd gives up on balancing particular nodes after too
|
||
* many failures to reclaim anything from them and goes to
|
||
* sleep. On reclaim progress, reset the failure counter. A
|
||
* successful direct reclaim run will revive a dormant kswapd.
|
||
*/
|
||
if (reclaimable)
|
||
pgdat->kswapd_failures = 0;
|
||
}
|
||
|
||
/*
|
||
* Returns true if compaction should go ahead for a costly-order request, or
|
||
* the allocation would already succeed without compaction. Return false if we
|
||
* should reclaim first.
|
||
*/
|
||
static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
|
||
{
|
||
unsigned long watermark;
|
||
|
||
if (!gfp_compaction_allowed(sc->gfp_mask))
|
||
return false;
|
||
|
||
/* Allocation can already succeed, nothing to do */
|
||
if (zone_watermark_ok(zone, sc->order, min_wmark_pages(zone),
|
||
sc->reclaim_idx, 0))
|
||
return true;
|
||
|
||
/* Compaction cannot yet proceed. Do reclaim. */
|
||
if (!compaction_suitable(zone, sc->order, sc->reclaim_idx))
|
||
return false;
|
||
|
||
/*
|
||
* Compaction is already possible, but it takes time to run and there
|
||
* are potentially other callers using the pages just freed. So proceed
|
||
* with reclaim to make a buffer of free pages available to give
|
||
* compaction a reasonable chance of completing and allocating the page.
|
||
* Note that we won't actually reclaim the whole buffer in one attempt
|
||
* as the target watermark in should_continue_reclaim() is lower. But if
|
||
* we are already above the high+gap watermark, don't reclaim at all.
|
||
*/
|
||
watermark = high_wmark_pages(zone) + compact_gap(sc->order);
|
||
|
||
return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx);
|
||
}
|
||
|
||
static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc)
|
||
{
|
||
/*
|
||
* If reclaim is making progress greater than 12% efficiency then
|
||
* wake all the NOPROGRESS throttled tasks.
|
||
*/
|
||
if (sc->nr_reclaimed > (sc->nr_scanned >> 3)) {
|
||
wait_queue_head_t *wqh;
|
||
|
||
wqh = &pgdat->reclaim_wait[VMSCAN_THROTTLE_NOPROGRESS];
|
||
if (waitqueue_active(wqh))
|
||
wake_up(wqh);
|
||
|
||
return;
|
||
}
|
||
|
||
/*
|
||
* Do not throttle kswapd or cgroup reclaim on NOPROGRESS as it will
|
||
* throttle on VMSCAN_THROTTLE_WRITEBACK if there are too many pages
|
||
* under writeback and marked for immediate reclaim at the tail of the
|
||
* LRU.
|
||
*/
|
||
if (current_is_kswapd() || cgroup_reclaim(sc))
|
||
return;
|
||
|
||
/* Throttle if making no progress at high prioities. */
|
||
if (sc->priority == 1 && !sc->nr_reclaimed)
|
||
reclaim_throttle(pgdat, VMSCAN_THROTTLE_NOPROGRESS);
|
||
}
|
||
|
||
/*
|
||
* This is the direct reclaim path, for page-allocating processes. We only
|
||
* try to reclaim pages from zones which will satisfy the caller's allocation
|
||
* request.
|
||
*
|
||
* If a zone is deemed to be full of pinned pages then just give it a light
|
||
* scan then give up on it.
|
||
*/
|
||
static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
|
||
{
|
||
struct zoneref *z;
|
||
struct zone *zone;
|
||
unsigned long nr_soft_reclaimed;
|
||
unsigned long nr_soft_scanned;
|
||
gfp_t orig_mask;
|
||
pg_data_t *last_pgdat = NULL;
|
||
pg_data_t *first_pgdat = NULL;
|
||
|
||
/*
|
||
* If the number of buffer_heads in the machine exceeds the maximum
|
||
* allowed level, force direct reclaim to scan the highmem zone as
|
||
* highmem pages could be pinning lowmem pages storing buffer_heads
|
||
*/
|
||
orig_mask = sc->gfp_mask;
|
||
if (buffer_heads_over_limit) {
|
||
sc->gfp_mask |= __GFP_HIGHMEM;
|
||
sc->reclaim_idx = gfp_zone(sc->gfp_mask);
|
||
}
|
||
|
||
for_each_zone_zonelist_nodemask(zone, z, zonelist,
|
||
sc->reclaim_idx, sc->nodemask) {
|
||
/*
|
||
* Take care memory controller reclaiming has small influence
|
||
* to global LRU.
|
||
*/
|
||
if (!cgroup_reclaim(sc)) {
|
||
if (!cpuset_zone_allowed(zone,
|
||
GFP_KERNEL | __GFP_HARDWALL))
|
||
continue;
|
||
|
||
/*
|
||
* If we already have plenty of memory free for
|
||
* compaction in this zone, don't free any more.
|
||
* Even though compaction is invoked for any
|
||
* non-zero order, only frequent costly order
|
||
* reclamation is disruptive enough to become a
|
||
* noticeable problem, like transparent huge
|
||
* page allocations.
|
||
*/
|
||
if (IS_ENABLED(CONFIG_COMPACTION) &&
|
||
sc->order > PAGE_ALLOC_COSTLY_ORDER &&
|
||
compaction_ready(zone, sc)) {
|
||
sc->compaction_ready = true;
|
||
continue;
|
||
}
|
||
|
||
/*
|
||
* Shrink each node in the zonelist once. If the
|
||
* zonelist is ordered by zone (not the default) then a
|
||
* node may be shrunk multiple times but in that case
|
||
* the user prefers lower zones being preserved.
|
||
*/
|
||
if (zone->zone_pgdat == last_pgdat)
|
||
continue;
|
||
|
||
/*
|
||
* This steals pages from memory cgroups over softlimit
|
||
* and returns the number of reclaimed pages and
|
||
* scanned pages. This works for global memory pressure
|
||
* and balancing, not for a memcg's limit.
|
||
*/
|
||
nr_soft_scanned = 0;
|
||
nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat,
|
||
sc->order, sc->gfp_mask,
|
||
&nr_soft_scanned);
|
||
sc->nr_reclaimed += nr_soft_reclaimed;
|
||
sc->nr_scanned += nr_soft_scanned;
|
||
/* need some check for avoid more shrink_zone() */
|
||
}
|
||
|
||
if (!first_pgdat)
|
||
first_pgdat = zone->zone_pgdat;
|
||
|
||
/* See comment about same check for global reclaim above */
|
||
if (zone->zone_pgdat == last_pgdat)
|
||
continue;
|
||
last_pgdat = zone->zone_pgdat;
|
||
shrink_node(zone->zone_pgdat, sc);
|
||
}
|
||
|
||
if (first_pgdat)
|
||
consider_reclaim_throttle(first_pgdat, sc);
|
||
|
||
/*
|
||
* Restore to original mask to avoid the impact on the caller if we
|
||
* promoted it to __GFP_HIGHMEM.
|
||
*/
|
||
sc->gfp_mask = orig_mask;
|
||
}
|
||
|
||
static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat)
|
||
{
|
||
struct lruvec *target_lruvec;
|
||
unsigned long refaults;
|
||
|
||
if (lru_gen_enabled())
|
||
return;
|
||
|
||
target_lruvec = mem_cgroup_lruvec(target_memcg, pgdat);
|
||
refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_ANON);
|
||
target_lruvec->refaults[WORKINGSET_ANON] = refaults;
|
||
refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_FILE);
|
||
target_lruvec->refaults[WORKINGSET_FILE] = refaults;
|
||
}
|
||
|
||
/*
|
||
* This is the main entry point to direct page reclaim.
|
||
*
|
||
* If a full scan of the inactive list fails to free enough memory then we
|
||
* are "out of memory" and something needs to be killed.
|
||
*
|
||
* If the caller is !__GFP_FS then the probability of a failure is reasonably
|
||
* high - the zone may be full of dirty or under-writeback pages, which this
|
||
* caller can't do much about. We kick the writeback threads and take explicit
|
||
* naps in the hope that some of these pages can be written. But if the
|
||
* allocating task holds filesystem locks which prevent writeout this might not
|
||
* work, and the allocation attempt will fail.
|
||
*
|
||
* returns: 0, if no pages reclaimed
|
||
* else, the number of pages reclaimed
|
||
*/
|
||
static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
|
||
struct scan_control *sc)
|
||
{
|
||
int initial_priority = sc->priority;
|
||
pg_data_t *last_pgdat;
|
||
struct zoneref *z;
|
||
struct zone *zone;
|
||
retry:
|
||
delayacct_freepages_start();
|
||
|
||
if (!cgroup_reclaim(sc))
|
||
__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
|
||
|
||
do {
|
||
if (!sc->proactive)
|
||
vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
|
||
sc->priority);
|
||
sc->nr_scanned = 0;
|
||
shrink_zones(zonelist, sc);
|
||
|
||
if (sc->nr_reclaimed >= sc->nr_to_reclaim)
|
||
break;
|
||
|
||
if (sc->compaction_ready)
|
||
break;
|
||
|
||
/*
|
||
* If we're getting trouble reclaiming, start doing
|
||
* writepage even in laptop mode.
|
||
*/
|
||
if (sc->priority < DEF_PRIORITY - 2)
|
||
sc->may_writepage = 1;
|
||
} while (--sc->priority >= 0);
|
||
|
||
last_pgdat = NULL;
|
||
for_each_zone_zonelist_nodemask(zone, z, zonelist, sc->reclaim_idx,
|
||
sc->nodemask) {
|
||
if (zone->zone_pgdat == last_pgdat)
|
||
continue;
|
||
last_pgdat = zone->zone_pgdat;
|
||
|
||
snapshot_refaults(sc->target_mem_cgroup, zone->zone_pgdat);
|
||
|
||
if (cgroup_reclaim(sc)) {
|
||
struct lruvec *lruvec;
|
||
|
||
lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup,
|
||
zone->zone_pgdat);
|
||
clear_bit(LRUVEC_CGROUP_CONGESTED, &lruvec->flags);
|
||
}
|
||
}
|
||
|
||
delayacct_freepages_end();
|
||
|
||
if (sc->nr_reclaimed)
|
||
return sc->nr_reclaimed;
|
||
|
||
/* Aborted reclaim to try compaction? don't OOM, then */
|
||
if (sc->compaction_ready)
|
||
return 1;
|
||
|
||
/*
|
||
* We make inactive:active ratio decisions based on the node's
|
||
* composition of memory, but a restrictive reclaim_idx or a
|
||
* memory.low cgroup setting can exempt large amounts of
|
||
* memory from reclaim. Neither of which are very common, so
|
||
* instead of doing costly eligibility calculations of the
|
||
* entire cgroup subtree up front, we assume the estimates are
|
||
* good, and retry with forcible deactivation if that fails.
|
||
*/
|
||
if (sc->skipped_deactivate) {
|
||
sc->priority = initial_priority;
|
||
sc->force_deactivate = 1;
|
||
sc->skipped_deactivate = 0;
|
||
goto retry;
|
||
}
|
||
|
||
/* Untapped cgroup reserves? Don't OOM, retry. */
|
||
if (sc->memcg_low_skipped) {
|
||
sc->priority = initial_priority;
|
||
sc->force_deactivate = 0;
|
||
sc->memcg_low_reclaim = 1;
|
||
sc->memcg_low_skipped = 0;
|
||
goto retry;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static bool allow_direct_reclaim(pg_data_t *pgdat)
|
||
{
|
||
struct zone *zone;
|
||
unsigned long pfmemalloc_reserve = 0;
|
||
unsigned long free_pages = 0;
|
||
int i;
|
||
bool wmark_ok;
|
||
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
|
||
return true;
|
||
|
||
for (i = 0; i <= ZONE_NORMAL; i++) {
|
||
zone = &pgdat->node_zones[i];
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (!zone_reclaimable_pages(zone))
|
||
continue;
|
||
|
||
pfmemalloc_reserve += min_wmark_pages(zone);
|
||
free_pages += zone_page_state_snapshot(zone, NR_FREE_PAGES);
|
||
}
|
||
|
||
/* If there are no reserves (unexpected config) then do not throttle */
|
||
if (!pfmemalloc_reserve)
|
||
return true;
|
||
|
||
wmark_ok = free_pages > pfmemalloc_reserve / 2;
|
||
|
||
/* kswapd must be awake if processes are being throttled */
|
||
if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) {
|
||
if (READ_ONCE(pgdat->kswapd_highest_zoneidx) > ZONE_NORMAL)
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, ZONE_NORMAL);
|
||
|
||
wake_up_interruptible(&pgdat->kswapd_wait);
|
||
}
|
||
|
||
return wmark_ok;
|
||
}
|
||
|
||
/*
|
||
* Throttle direct reclaimers if backing storage is backed by the network
|
||
* and the PFMEMALLOC reserve for the preferred node is getting dangerously
|
||
* depleted. kswapd will continue to make progress and wake the processes
|
||
* when the low watermark is reached.
|
||
*
|
||
* Returns true if a fatal signal was delivered during throttling. If this
|
||
* happens, the page allocator should not consider triggering the OOM killer.
|
||
*/
|
||
static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
|
||
nodemask_t *nodemask)
|
||
{
|
||
struct zoneref *z;
|
||
struct zone *zone;
|
||
pg_data_t *pgdat = NULL;
|
||
|
||
/*
|
||
* Kernel threads should not be throttled as they may be indirectly
|
||
* responsible for cleaning pages necessary for reclaim to make forward
|
||
* progress. kjournald for example may enter direct reclaim while
|
||
* committing a transaction where throttling it could forcing other
|
||
* processes to block on log_wait_commit().
|
||
*/
|
||
if (current->flags & PF_KTHREAD)
|
||
goto out;
|
||
|
||
/*
|
||
* If a fatal signal is pending, this process should not throttle.
|
||
* It should return quickly so it can exit and free its memory
|
||
*/
|
||
if (fatal_signal_pending(current))
|
||
goto out;
|
||
|
||
/*
|
||
* Check if the pfmemalloc reserves are ok by finding the first node
|
||
* with a usable ZONE_NORMAL or lower zone. The expectation is that
|
||
* GFP_KERNEL will be required for allocating network buffers when
|
||
* swapping over the network so ZONE_HIGHMEM is unusable.
|
||
*
|
||
* Throttling is based on the first usable node and throttled processes
|
||
* wait on a queue until kswapd makes progress and wakes them. There
|
||
* is an affinity then between processes waking up and where reclaim
|
||
* progress has been made assuming the process wakes on the same node.
|
||
* More importantly, processes running on remote nodes will not compete
|
||
* for remote pfmemalloc reserves and processes on different nodes
|
||
* should make reasonable progress.
|
||
*/
|
||
for_each_zone_zonelist_nodemask(zone, z, zonelist,
|
||
gfp_zone(gfp_mask), nodemask) {
|
||
if (zone_idx(zone) > ZONE_NORMAL)
|
||
continue;
|
||
|
||
/* Throttle based on the first usable node */
|
||
pgdat = zone->zone_pgdat;
|
||
if (allow_direct_reclaim(pgdat))
|
||
goto out;
|
||
break;
|
||
}
|
||
|
||
/* If no zone was usable by the allocation flags then do not throttle */
|
||
if (!pgdat)
|
||
goto out;
|
||
|
||
/* Account for the throttling */
|
||
count_vm_event(PGSCAN_DIRECT_THROTTLE);
|
||
|
||
/*
|
||
* If the caller cannot enter the filesystem, it's possible that it
|
||
* is due to the caller holding an FS lock or performing a journal
|
||
* transaction in the case of a filesystem like ext[3|4]. In this case,
|
||
* it is not safe to block on pfmemalloc_wait as kswapd could be
|
||
* blocked waiting on the same lock. Instead, throttle for up to a
|
||
* second before continuing.
|
||
*/
|
||
if (!(gfp_mask & __GFP_FS))
|
||
wait_event_interruptible_timeout(pgdat->pfmemalloc_wait,
|
||
allow_direct_reclaim(pgdat), HZ);
|
||
else
|
||
/* Throttle until kswapd wakes the process */
|
||
wait_event_killable(zone->zone_pgdat->pfmemalloc_wait,
|
||
allow_direct_reclaim(pgdat));
|
||
|
||
if (fatal_signal_pending(current))
|
||
return true;
|
||
|
||
out:
|
||
return false;
|
||
}
|
||
|
||
unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
|
||
gfp_t gfp_mask, nodemask_t *nodemask)
|
||
{
|
||
unsigned long nr_reclaimed;
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
||
.gfp_mask = current_gfp_context(gfp_mask),
|
||
.reclaim_idx = gfp_zone(gfp_mask),
|
||
.order = order,
|
||
.nodemask = nodemask,
|
||
.priority = DEF_PRIORITY,
|
||
.may_writepage = !laptop_mode,
|
||
.may_unmap = 1,
|
||
.may_swap = 1,
|
||
};
|
||
|
||
/*
|
||
* scan_control uses s8 fields for order, priority, and reclaim_idx.
|
||
* Confirm they are large enough for max values.
|
||
*/
|
||
BUILD_BUG_ON(MAX_PAGE_ORDER >= S8_MAX);
|
||
BUILD_BUG_ON(DEF_PRIORITY > S8_MAX);
|
||
BUILD_BUG_ON(MAX_NR_ZONES > S8_MAX);
|
||
|
||
/*
|
||
* Do not enter reclaim if fatal signal was delivered while throttled.
|
||
* 1 is returned so that the page allocator does not OOM kill at this
|
||
* point.
|
||
*/
|
||
if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask))
|
||
return 1;
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
trace_mm_vmscan_direct_reclaim_begin(order, sc.gfp_mask);
|
||
|
||
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
||
|
||
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
|
||
#ifdef CONFIG_MEMCG
|
||
|
||
/* Only used by soft limit reclaim. Do not reuse for anything else. */
|
||
unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
|
||
gfp_t gfp_mask, bool noswap,
|
||
pg_data_t *pgdat,
|
||
unsigned long *nr_scanned)
|
||
{
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = SWAP_CLUSTER_MAX,
|
||
.target_mem_cgroup = memcg,
|
||
.may_writepage = !laptop_mode,
|
||
.may_unmap = 1,
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.may_swap = !noswap,
|
||
};
|
||
|
||
WARN_ON_ONCE(!current->reclaim_state);
|
||
|
||
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
|
||
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
|
||
|
||
trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
|
||
sc.gfp_mask);
|
||
|
||
/*
|
||
* NOTE: Although we can get the priority field, using it
|
||
* here is not a good idea, since it limits the pages we can scan.
|
||
* if we don't reclaim here, the shrink_node from balance_pgdat
|
||
* will pick up pages from other mem cgroup's as well. We hack
|
||
* the priority and make it zero.
|
||
*/
|
||
shrink_lruvec(lruvec, &sc);
|
||
|
||
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
|
||
|
||
*nr_scanned = sc.nr_scanned;
|
||
|
||
return sc.nr_reclaimed;
|
||
}
|
||
|
||
unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
|
||
unsigned long nr_pages,
|
||
gfp_t gfp_mask,
|
||
unsigned int reclaim_options)
|
||
{
|
||
unsigned long nr_reclaimed;
|
||
unsigned int noreclaim_flag;
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
|
||
.gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) |
|
||
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.target_mem_cgroup = memcg,
|
||
.priority = DEF_PRIORITY,
|
||
.may_writepage = !laptop_mode,
|
||
.may_unmap = 1,
|
||
.may_swap = !!(reclaim_options & MEMCG_RECLAIM_MAY_SWAP),
|
||
.proactive = !!(reclaim_options & MEMCG_RECLAIM_PROACTIVE),
|
||
};
|
||
/*
|
||
* Traverse the ZONELIST_FALLBACK zonelist of the current node to put
|
||
* equal pressure on all the nodes. This is based on the assumption that
|
||
* the reclaim does not bail out early.
|
||
*/
|
||
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask);
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
|
||
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
||
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
#endif
|
||
|
||
static void kswapd_age_node(struct pglist_data *pgdat, struct scan_control *sc)
|
||
{
|
||
struct mem_cgroup *memcg;
|
||
struct lruvec *lruvec;
|
||
|
||
if (lru_gen_enabled()) {
|
||
lru_gen_age_node(pgdat, sc);
|
||
return;
|
||
}
|
||
|
||
if (!can_age_anon_pages(pgdat, sc))
|
||
return;
|
||
|
||
lruvec = mem_cgroup_lruvec(NULL, pgdat);
|
||
if (!inactive_is_low(lruvec, LRU_INACTIVE_ANON))
|
||
return;
|
||
|
||
memcg = mem_cgroup_iter(NULL, NULL, NULL);
|
||
do {
|
||
lruvec = mem_cgroup_lruvec(memcg, pgdat);
|
||
shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
|
||
sc, LRU_ACTIVE_ANON);
|
||
memcg = mem_cgroup_iter(NULL, memcg, NULL);
|
||
} while (memcg);
|
||
}
|
||
|
||
static bool pgdat_watermark_boosted(pg_data_t *pgdat, int highest_zoneidx)
|
||
{
|
||
int i;
|
||
struct zone *zone;
|
||
|
||
/*
|
||
* Check for watermark boosts top-down as the higher zones
|
||
* are more likely to be boosted. Both watermarks and boosts
|
||
* should not be checked at the same time as reclaim would
|
||
* start prematurely when there is no boosting and a lower
|
||
* zone is balanced.
|
||
*/
|
||
for (i = highest_zoneidx; i >= 0; i--) {
|
||
zone = pgdat->node_zones + i;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (zone->watermark_boost)
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* Returns true if there is an eligible zone balanced for the request order
|
||
* and highest_zoneidx
|
||
*/
|
||
static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx)
|
||
{
|
||
int i;
|
||
unsigned long mark = -1;
|
||
struct zone *zone;
|
||
|
||
/*
|
||
* Check watermarks bottom-up as lower zones are more likely to
|
||
* meet watermarks.
|
||
*/
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
zone = pgdat->node_zones + i;
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
|
||
mark = wmark_pages(zone, WMARK_PROMO);
|
||
else
|
||
mark = high_wmark_pages(zone);
|
||
if (zone_watermark_ok_safe(zone, order, mark, highest_zoneidx))
|
||
return true;
|
||
}
|
||
|
||
/*
|
||
* If a node has no managed zone within highest_zoneidx, it does not
|
||
* need balancing by definition. This can happen if a zone-restricted
|
||
* allocation tries to wake a remote kswapd.
|
||
*/
|
||
if (mark == -1)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Clear pgdat state for congested, dirty or under writeback. */
|
||
static void clear_pgdat_congested(pg_data_t *pgdat)
|
||
{
|
||
struct lruvec *lruvec = mem_cgroup_lruvec(NULL, pgdat);
|
||
|
||
clear_bit(LRUVEC_NODE_CONGESTED, &lruvec->flags);
|
||
clear_bit(LRUVEC_CGROUP_CONGESTED, &lruvec->flags);
|
||
clear_bit(PGDAT_DIRTY, &pgdat->flags);
|
||
clear_bit(PGDAT_WRITEBACK, &pgdat->flags);
|
||
}
|
||
|
||
/*
|
||
* Prepare kswapd for sleeping. This verifies that there are no processes
|
||
* waiting in throttle_direct_reclaim() and that watermarks have been met.
|
||
*
|
||
* Returns true if kswapd is ready to sleep
|
||
*/
|
||
static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order,
|
||
int highest_zoneidx)
|
||
{
|
||
/*
|
||
* The throttled processes are normally woken up in balance_pgdat() as
|
||
* soon as allow_direct_reclaim() is true. But there is a potential
|
||
* race between when kswapd checks the watermarks and a process gets
|
||
* throttled. There is also a potential race if processes get
|
||
* throttled, kswapd wakes, a large process exits thereby balancing the
|
||
* zones, which causes kswapd to exit balance_pgdat() before reaching
|
||
* the wake up checks. If kswapd is going to sleep, no process should
|
||
* be sleeping on pfmemalloc_wait, so wake them now if necessary. If
|
||
* the wake up is premature, processes will wake kswapd and get
|
||
* throttled again. The difference from wake ups in balance_pgdat() is
|
||
* that here we are under prepare_to_wait().
|
||
*/
|
||
if (waitqueue_active(&pgdat->pfmemalloc_wait))
|
||
wake_up_all(&pgdat->pfmemalloc_wait);
|
||
|
||
/* Hopeless node, leave it to direct reclaim */
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES)
|
||
return true;
|
||
|
||
if (pgdat_balanced(pgdat, order, highest_zoneidx)) {
|
||
clear_pgdat_congested(pgdat);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/*
|
||
* kswapd shrinks a node of pages that are at or below the highest usable
|
||
* zone that is currently unbalanced.
|
||
*
|
||
* Returns true if kswapd scanned at least the requested number of pages to
|
||
* reclaim or if the lack of progress was due to pages under writeback.
|
||
* This is used to determine if the scanning priority needs to be raised.
|
||
*/
|
||
static bool kswapd_shrink_node(pg_data_t *pgdat,
|
||
struct scan_control *sc)
|
||
{
|
||
struct zone *zone;
|
||
int z;
|
||
|
||
/* Reclaim a number of pages proportional to the number of zones */
|
||
sc->nr_to_reclaim = 0;
|
||
for (z = 0; z <= sc->reclaim_idx; z++) {
|
||
zone = pgdat->node_zones + z;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX);
|
||
}
|
||
|
||
/*
|
||
* Historically care was taken to put equal pressure on all zones but
|
||
* now pressure is applied based on node LRU order.
|
||
*/
|
||
shrink_node(pgdat, sc);
|
||
|
||
/*
|
||
* Fragmentation may mean that the system cannot be rebalanced for
|
||
* high-order allocations. If twice the allocation size has been
|
||
* reclaimed then recheck watermarks only at order-0 to prevent
|
||
* excessive reclaim. Assume that a process requested a high-order
|
||
* can direct reclaim/compact.
|
||
*/
|
||
if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order))
|
||
sc->order = 0;
|
||
|
||
return sc->nr_scanned >= sc->nr_to_reclaim;
|
||
}
|
||
|
||
/* Page allocator PCP high watermark is lowered if reclaim is active. */
|
||
static inline void
|
||
update_reclaim_active(pg_data_t *pgdat, int highest_zoneidx, bool active)
|
||
{
|
||
int i;
|
||
struct zone *zone;
|
||
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
zone = pgdat->node_zones + i;
|
||
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
if (active)
|
||
set_bit(ZONE_RECLAIM_ACTIVE, &zone->flags);
|
||
else
|
||
clear_bit(ZONE_RECLAIM_ACTIVE, &zone->flags);
|
||
}
|
||
}
|
||
|
||
static inline void
|
||
set_reclaim_active(pg_data_t *pgdat, int highest_zoneidx)
|
||
{
|
||
update_reclaim_active(pgdat, highest_zoneidx, true);
|
||
}
|
||
|
||
static inline void
|
||
clear_reclaim_active(pg_data_t *pgdat, int highest_zoneidx)
|
||
{
|
||
update_reclaim_active(pgdat, highest_zoneidx, false);
|
||
}
|
||
|
||
/*
|
||
* For kswapd, balance_pgdat() will reclaim pages across a node from zones
|
||
* that are eligible for use by the caller until at least one zone is
|
||
* balanced.
|
||
*
|
||
* Returns the order kswapd finished reclaiming at.
|
||
*
|
||
* kswapd scans the zones in the highmem->normal->dma direction. It skips
|
||
* zones which have free_pages > high_wmark_pages(zone), but once a zone is
|
||
* found to have free_pages <= high_wmark_pages(zone), any page in that zone
|
||
* or lower is eligible for reclaim until at least one usable zone is
|
||
* balanced.
|
||
*/
|
||
static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)
|
||
{
|
||
int i;
|
||
unsigned long nr_soft_reclaimed;
|
||
unsigned long nr_soft_scanned;
|
||
unsigned long pflags;
|
||
unsigned long nr_boost_reclaim;
|
||
unsigned long zone_boosts[MAX_NR_ZONES] = { 0, };
|
||
bool boosted;
|
||
struct zone *zone;
|
||
struct scan_control sc = {
|
||
.gfp_mask = GFP_KERNEL,
|
||
.order = order,
|
||
.may_unmap = 1,
|
||
};
|
||
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
psi_memstall_enter(&pflags);
|
||
__fs_reclaim_acquire(_THIS_IP_);
|
||
|
||
count_vm_event(PAGEOUTRUN);
|
||
|
||
/*
|
||
* Account for the reclaim boost. Note that the zone boost is left in
|
||
* place so that parallel allocations that are near the watermark will
|
||
* stall or direct reclaim until kswapd is finished.
|
||
*/
|
||
nr_boost_reclaim = 0;
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
zone = pgdat->node_zones + i;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
nr_boost_reclaim += zone->watermark_boost;
|
||
zone_boosts[i] = zone->watermark_boost;
|
||
}
|
||
boosted = nr_boost_reclaim;
|
||
|
||
restart:
|
||
set_reclaim_active(pgdat, highest_zoneidx);
|
||
sc.priority = DEF_PRIORITY;
|
||
do {
|
||
unsigned long nr_reclaimed = sc.nr_reclaimed;
|
||
bool raise_priority = true;
|
||
bool balanced;
|
||
bool ret;
|
||
|
||
sc.reclaim_idx = highest_zoneidx;
|
||
|
||
/*
|
||
* If the number of buffer_heads exceeds the maximum allowed
|
||
* then consider reclaiming from all zones. This has a dual
|
||
* purpose -- on 64-bit systems it is expected that
|
||
* buffer_heads are stripped during active rotation. On 32-bit
|
||
* systems, highmem pages can pin lowmem memory and shrinking
|
||
* buffers can relieve lowmem pressure. Reclaim may still not
|
||
* go ahead if all eligible zones for the original allocation
|
||
* request are balanced to avoid excessive reclaim from kswapd.
|
||
*/
|
||
if (buffer_heads_over_limit) {
|
||
for (i = MAX_NR_ZONES - 1; i >= 0; i--) {
|
||
zone = pgdat->node_zones + i;
|
||
if (!managed_zone(zone))
|
||
continue;
|
||
|
||
sc.reclaim_idx = i;
|
||
break;
|
||
}
|
||
}
|
||
|
||
/*
|
||
* If the pgdat is imbalanced then ignore boosting and preserve
|
||
* the watermarks for a later time and restart. Note that the
|
||
* zone watermarks will be still reset at the end of balancing
|
||
* on the grounds that the normal reclaim should be enough to
|
||
* re-evaluate if boosting is required when kswapd next wakes.
|
||
*/
|
||
balanced = pgdat_balanced(pgdat, sc.order, highest_zoneidx);
|
||
if (!balanced && nr_boost_reclaim) {
|
||
nr_boost_reclaim = 0;
|
||
goto restart;
|
||
}
|
||
|
||
/*
|
||
* If boosting is not active then only reclaim if there are no
|
||
* eligible zones. Note that sc.reclaim_idx is not used as
|
||
* buffer_heads_over_limit may have adjusted it.
|
||
*/
|
||
if (!nr_boost_reclaim && balanced)
|
||
goto out;
|
||
|
||
/* Limit the priority of boosting to avoid reclaim writeback */
|
||
if (nr_boost_reclaim && sc.priority == DEF_PRIORITY - 2)
|
||
raise_priority = false;
|
||
|
||
/*
|
||
* Do not writeback or swap pages for boosted reclaim. The
|
||
* intent is to relieve pressure not issue sub-optimal IO
|
||
* from reclaim context. If no pages are reclaimed, the
|
||
* reclaim will be aborted.
|
||
*/
|
||
sc.may_writepage = !laptop_mode && !nr_boost_reclaim;
|
||
sc.may_swap = !nr_boost_reclaim;
|
||
|
||
/*
|
||
* Do some background aging, to give pages a chance to be
|
||
* referenced before reclaiming. All pages are rotated
|
||
* regardless of classzone as this is about consistent aging.
|
||
*/
|
||
kswapd_age_node(pgdat, &sc);
|
||
|
||
/*
|
||
* If we're getting trouble reclaiming, start doing writepage
|
||
* even in laptop mode.
|
||
*/
|
||
if (sc.priority < DEF_PRIORITY - 2)
|
||
sc.may_writepage = 1;
|
||
|
||
/* Call soft limit reclaim before calling shrink_node. */
|
||
sc.nr_scanned = 0;
|
||
nr_soft_scanned = 0;
|
||
nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order,
|
||
sc.gfp_mask, &nr_soft_scanned);
|
||
sc.nr_reclaimed += nr_soft_reclaimed;
|
||
|
||
/*
|
||
* There should be no need to raise the scanning priority if
|
||
* enough pages are already being scanned that that high
|
||
* watermark would be met at 100% efficiency.
|
||
*/
|
||
if (kswapd_shrink_node(pgdat, &sc))
|
||
raise_priority = false;
|
||
|
||
/*
|
||
* If the low watermark is met there is no need for processes
|
||
* to be throttled on pfmemalloc_wait as they should not be
|
||
* able to safely make forward progress. Wake them
|
||
*/
|
||
if (waitqueue_active(&pgdat->pfmemalloc_wait) &&
|
||
allow_direct_reclaim(pgdat))
|
||
wake_up_all(&pgdat->pfmemalloc_wait);
|
||
|
||
/* Check if kswapd should be suspending */
|
||
__fs_reclaim_release(_THIS_IP_);
|
||
ret = try_to_freeze();
|
||
__fs_reclaim_acquire(_THIS_IP_);
|
||
if (ret || kthread_should_stop())
|
||
break;
|
||
|
||
/*
|
||
* Raise priority if scanning rate is too low or there was no
|
||
* progress in reclaiming pages
|
||
*/
|
||
nr_reclaimed = sc.nr_reclaimed - nr_reclaimed;
|
||
nr_boost_reclaim -= min(nr_boost_reclaim, nr_reclaimed);
|
||
|
||
/*
|
||
* If reclaim made no progress for a boost, stop reclaim as
|
||
* IO cannot be queued and it could be an infinite loop in
|
||
* extreme circumstances.
|
||
*/
|
||
if (nr_boost_reclaim && !nr_reclaimed)
|
||
break;
|
||
|
||
if (raise_priority || !nr_reclaimed)
|
||
sc.priority--;
|
||
} while (sc.priority >= 1);
|
||
|
||
if (!sc.nr_reclaimed)
|
||
pgdat->kswapd_failures++;
|
||
|
||
out:
|
||
clear_reclaim_active(pgdat, highest_zoneidx);
|
||
|
||
/* If reclaim was boosted, account for the reclaim done in this pass */
|
||
if (boosted) {
|
||
unsigned long flags;
|
||
|
||
for (i = 0; i <= highest_zoneidx; i++) {
|
||
if (!zone_boosts[i])
|
||
continue;
|
||
|
||
/* Increments are under the zone lock */
|
||
zone = pgdat->node_zones + i;
|
||
spin_lock_irqsave(&zone->lock, flags);
|
||
zone->watermark_boost -= min(zone->watermark_boost, zone_boosts[i]);
|
||
spin_unlock_irqrestore(&zone->lock, flags);
|
||
}
|
||
|
||
/*
|
||
* As there is now likely space, wakeup kcompact to defragment
|
||
* pageblocks.
|
||
*/
|
||
wakeup_kcompactd(pgdat, pageblock_order, highest_zoneidx);
|
||
}
|
||
|
||
snapshot_refaults(NULL, pgdat);
|
||
__fs_reclaim_release(_THIS_IP_);
|
||
psi_memstall_leave(&pflags);
|
||
set_task_reclaim_state(current, NULL);
|
||
|
||
/*
|
||
* Return the order kswapd stopped reclaiming at as
|
||
* prepare_kswapd_sleep() takes it into account. If another caller
|
||
* entered the allocator slow path while kswapd was awake, order will
|
||
* remain at the higher level.
|
||
*/
|
||
return sc.order;
|
||
}
|
||
|
||
/*
|
||
* The pgdat->kswapd_highest_zoneidx is used to pass the highest zone index to
|
||
* be reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is
|
||
* not a valid index then either kswapd runs for first time or kswapd couldn't
|
||
* sleep after previous reclaim attempt (node is still unbalanced). In that
|
||
* case return the zone index of the previous kswapd reclaim cycle.
|
||
*/
|
||
static enum zone_type kswapd_highest_zoneidx(pg_data_t *pgdat,
|
||
enum zone_type prev_highest_zoneidx)
|
||
{
|
||
enum zone_type curr_idx = READ_ONCE(pgdat->kswapd_highest_zoneidx);
|
||
|
||
return curr_idx == MAX_NR_ZONES ? prev_highest_zoneidx : curr_idx;
|
||
}
|
||
|
||
static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order,
|
||
unsigned int highest_zoneidx)
|
||
{
|
||
long remaining = 0;
|
||
DEFINE_WAIT(wait);
|
||
|
||
if (freezing(current) || kthread_should_stop())
|
||
return;
|
||
|
||
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
||
|
||
/*
|
||
* Try to sleep for a short interval. Note that kcompactd will only be
|
||
* woken if it is possible to sleep for a short interval. This is
|
||
* deliberate on the assumption that if reclaim cannot keep an
|
||
* eligible zone balanced that it's also unlikely that compaction will
|
||
* succeed.
|
||
*/
|
||
if (prepare_kswapd_sleep(pgdat, reclaim_order, highest_zoneidx)) {
|
||
/*
|
||
* Compaction records what page blocks it recently failed to
|
||
* isolate pages from and skips them in the future scanning.
|
||
* When kswapd is going to sleep, it is reasonable to assume
|
||
* that pages and compaction may succeed so reset the cache.
|
||
*/
|
||
reset_isolation_suitable(pgdat);
|
||
|
||
/*
|
||
* We have freed the memory, now we should compact it to make
|
||
* allocation of the requested order possible.
|
||
*/
|
||
wakeup_kcompactd(pgdat, alloc_order, highest_zoneidx);
|
||
|
||
remaining = schedule_timeout(HZ/10);
|
||
|
||
/*
|
||
* If woken prematurely then reset kswapd_highest_zoneidx and
|
||
* order. The values will either be from a wakeup request or
|
||
* the previous request that slept prematurely.
|
||
*/
|
||
if (remaining) {
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx,
|
||
kswapd_highest_zoneidx(pgdat,
|
||
highest_zoneidx));
|
||
|
||
if (READ_ONCE(pgdat->kswapd_order) < reclaim_order)
|
||
WRITE_ONCE(pgdat->kswapd_order, reclaim_order);
|
||
}
|
||
|
||
finish_wait(&pgdat->kswapd_wait, &wait);
|
||
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
|
||
}
|
||
|
||
/*
|
||
* After a short sleep, check if it was a premature sleep. If not, then
|
||
* go fully to sleep until explicitly woken up.
|
||
*/
|
||
if (!remaining &&
|
||
prepare_kswapd_sleep(pgdat, reclaim_order, highest_zoneidx)) {
|
||
trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
|
||
|
||
/*
|
||
* vmstat counters are not perfectly accurate and the estimated
|
||
* value for counters such as NR_FREE_PAGES can deviate from the
|
||
* true value by nr_online_cpus * threshold. To avoid the zone
|
||
* watermarks being breached while under pressure, we reduce the
|
||
* per-cpu vmstat threshold while kswapd is awake and restore
|
||
* them before going back to sleep.
|
||
*/
|
||
set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
|
||
|
||
if (!kthread_should_stop())
|
||
schedule();
|
||
|
||
set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
|
||
} else {
|
||
if (remaining)
|
||
count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
|
||
else
|
||
count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
|
||
}
|
||
finish_wait(&pgdat->kswapd_wait, &wait);
|
||
}
|
||
|
||
/*
|
||
* The background pageout daemon, started as a kernel thread
|
||
* from the init process.
|
||
*
|
||
* This basically trickles out pages so that we have _some_
|
||
* free memory available even if there is no other activity
|
||
* that frees anything up. This is needed for things like routing
|
||
* etc, where we otherwise might have all activity going on in
|
||
* asynchronous contexts that cannot page things out.
|
||
*
|
||
* If there are applications that are active memory-allocators
|
||
* (most normal use), this basically shouldn't matter.
|
||
*/
|
||
static int kswapd(void *p)
|
||
{
|
||
unsigned int alloc_order, reclaim_order;
|
||
unsigned int highest_zoneidx = MAX_NR_ZONES - 1;
|
||
pg_data_t *pgdat = (pg_data_t *)p;
|
||
struct task_struct *tsk = current;
|
||
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
|
||
|
||
if (!cpumask_empty(cpumask))
|
||
set_cpus_allowed_ptr(tsk, cpumask);
|
||
|
||
/*
|
||
* Tell the memory management that we're a "memory allocator",
|
||
* and that if we need more memory we should get access to it
|
||
* regardless (see "__alloc_pages()"). "kswapd" should
|
||
* never get caught in the normal page freeing logic.
|
||
*
|
||
* (Kswapd normally doesn't need memory anyway, but sometimes
|
||
* you need a small amount of memory in order to be able to
|
||
* page out something else, and this flag essentially protects
|
||
* us from recursively trying to free more memory as we're
|
||
* trying to free the first piece of memory in the first place).
|
||
*/
|
||
tsk->flags |= PF_MEMALLOC | PF_KSWAPD;
|
||
set_freezable();
|
||
|
||
WRITE_ONCE(pgdat->kswapd_order, 0);
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, MAX_NR_ZONES);
|
||
atomic_set(&pgdat->nr_writeback_throttled, 0);
|
||
for ( ; ; ) {
|
||
bool ret;
|
||
|
||
alloc_order = reclaim_order = READ_ONCE(pgdat->kswapd_order);
|
||
highest_zoneidx = kswapd_highest_zoneidx(pgdat,
|
||
highest_zoneidx);
|
||
|
||
kswapd_try_sleep:
|
||
kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order,
|
||
highest_zoneidx);
|
||
|
||
/* Read the new order and highest_zoneidx */
|
||
alloc_order = READ_ONCE(pgdat->kswapd_order);
|
||
highest_zoneidx = kswapd_highest_zoneidx(pgdat,
|
||
highest_zoneidx);
|
||
WRITE_ONCE(pgdat->kswapd_order, 0);
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, MAX_NR_ZONES);
|
||
|
||
ret = try_to_freeze();
|
||
if (kthread_should_stop())
|
||
break;
|
||
|
||
/*
|
||
* We can speed up thawing tasks if we don't call balance_pgdat
|
||
* after returning from the refrigerator
|
||
*/
|
||
if (ret)
|
||
continue;
|
||
|
||
/*
|
||
* Reclaim begins at the requested order but if a high-order
|
||
* reclaim fails then kswapd falls back to reclaiming for
|
||
* order-0. If that happens, kswapd will consider sleeping
|
||
* for the order it finished reclaiming at (reclaim_order)
|
||
* but kcompactd is woken to compact for the original
|
||
* request (alloc_order).
|
||
*/
|
||
trace_mm_vmscan_kswapd_wake(pgdat->node_id, highest_zoneidx,
|
||
alloc_order);
|
||
reclaim_order = balance_pgdat(pgdat, alloc_order,
|
||
highest_zoneidx);
|
||
if (reclaim_order < alloc_order)
|
||
goto kswapd_try_sleep;
|
||
}
|
||
|
||
tsk->flags &= ~(PF_MEMALLOC | PF_KSWAPD);
|
||
|
||
return 0;
|
||
}
|
||
|
||
/*
|
||
* A zone is low on free memory or too fragmented for high-order memory. If
|
||
* kswapd should reclaim (direct reclaim is deferred), wake it up for the zone's
|
||
* pgdat. It will wake up kcompactd after reclaiming memory. If kswapd reclaim
|
||
* has failed or is not needed, still wake up kcompactd if only compaction is
|
||
* needed.
|
||
*/
|
||
void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
|
||
enum zone_type highest_zoneidx)
|
||
{
|
||
pg_data_t *pgdat;
|
||
enum zone_type curr_idx;
|
||
|
||
if (!managed_zone(zone))
|
||
return;
|
||
|
||
if (!cpuset_zone_allowed(zone, gfp_flags))
|
||
return;
|
||
|
||
pgdat = zone->zone_pgdat;
|
||
curr_idx = READ_ONCE(pgdat->kswapd_highest_zoneidx);
|
||
|
||
if (curr_idx == MAX_NR_ZONES || curr_idx < highest_zoneidx)
|
||
WRITE_ONCE(pgdat->kswapd_highest_zoneidx, highest_zoneidx);
|
||
|
||
if (READ_ONCE(pgdat->kswapd_order) < order)
|
||
WRITE_ONCE(pgdat->kswapd_order, order);
|
||
|
||
if (!waitqueue_active(&pgdat->kswapd_wait))
|
||
return;
|
||
|
||
/* Hopeless node, leave it to direct reclaim if possible */
|
||
if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ||
|
||
(pgdat_balanced(pgdat, order, highest_zoneidx) &&
|
||
!pgdat_watermark_boosted(pgdat, highest_zoneidx))) {
|
||
/*
|
||
* There may be plenty of free memory available, but it's too
|
||
* fragmented for high-order allocations. Wake up kcompactd
|
||
* and rely on compaction_suitable() to determine if it's
|
||
* needed. If it fails, it will defer subsequent attempts to
|
||
* ratelimit its work.
|
||
*/
|
||
if (!(gfp_flags & __GFP_DIRECT_RECLAIM))
|
||
wakeup_kcompactd(pgdat, order, highest_zoneidx);
|
||
return;
|
||
}
|
||
|
||
trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, highest_zoneidx, order,
|
||
gfp_flags);
|
||
wake_up_interruptible(&pgdat->kswapd_wait);
|
||
}
|
||
|
||
#ifdef CONFIG_HIBERNATION
|
||
/*
|
||
* Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
|
||
* freed pages.
|
||
*
|
||
* Rather than trying to age LRUs the aim is to preserve the overall
|
||
* LRU order by reclaiming preferentially
|
||
* inactive > active > active referenced > active mapped
|
||
*/
|
||
unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
|
||
{
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = nr_to_reclaim,
|
||
.gfp_mask = GFP_HIGHUSER_MOVABLE,
|
||
.reclaim_idx = MAX_NR_ZONES - 1,
|
||
.priority = DEF_PRIORITY,
|
||
.may_writepage = 1,
|
||
.may_unmap = 1,
|
||
.may_swap = 1,
|
||
.hibernation_mode = 1,
|
||
};
|
||
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
|
||
unsigned long nr_reclaimed;
|
||
unsigned int noreclaim_flag;
|
||
|
||
fs_reclaim_acquire(sc.gfp_mask);
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
set_task_reclaim_state(current, &sc.reclaim_state);
|
||
|
||
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
|
||
|
||
set_task_reclaim_state(current, NULL);
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
fs_reclaim_release(sc.gfp_mask);
|
||
|
||
return nr_reclaimed;
|
||
}
|
||
#endif /* CONFIG_HIBERNATION */
|
||
|
||
/*
|
||
* This kswapd start function will be called by init and node-hot-add.
|
||
*/
|
||
void __meminit kswapd_run(int nid)
|
||
{
|
||
pg_data_t *pgdat = NODE_DATA(nid);
|
||
|
||
pgdat_kswapd_lock(pgdat);
|
||
if (!pgdat->kswapd) {
|
||
pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
|
||
if (IS_ERR(pgdat->kswapd)) {
|
||
/* failure at boot is fatal */
|
||
pr_err("Failed to start kswapd on node %d，ret=%ld\n",
|
||
nid, PTR_ERR(pgdat->kswapd));
|
||
BUG_ON(system_state < SYSTEM_RUNNING);
|
||
pgdat->kswapd = NULL;
|
||
}
|
||
}
|
||
pgdat_kswapd_unlock(pgdat);
|
||
}
|
||
|
||
/*
|
||
* Called by memory hotplug when all memory in a node is offlined. Caller must
|
||
* be holding mem_hotplug_begin/done().
|
||
*/
|
||
void __meminit kswapd_stop(int nid)
|
||
{
|
||
pg_data_t *pgdat = NODE_DATA(nid);
|
||
struct task_struct *kswapd;
|
||
|
||
pgdat_kswapd_lock(pgdat);
|
||
kswapd = pgdat->kswapd;
|
||
if (kswapd) {
|
||
kthread_stop(kswapd);
|
||
pgdat->kswapd = NULL;
|
||
}
|
||
pgdat_kswapd_unlock(pgdat);
|
||
}
|
||
|
||
static int __init kswapd_init(void)
|
||
{
|
||
int nid;
|
||
|
||
swap_setup();
|
||
for_each_node_state(nid, N_MEMORY)
|
||
kswapd_run(nid);
|
||
return 0;
|
||
}
|
||
|
||
module_init(kswapd_init)
|
||
|
||
#ifdef CONFIG_NUMA
|
||
/*
|
||
* Node reclaim mode
|
||
*
|
||
* If non-zero call node_reclaim when the number of free pages falls below
|
||
* the watermarks.
|
||
*/
|
||
int node_reclaim_mode __read_mostly;
|
||
|
||
/*
|
||
* Priority for NODE_RECLAIM. This determines the fraction of pages
|
||
* of a node considered for each zone_reclaim. 4 scans 1/16th of
|
||
* a zone.
|
||
*/
|
||
#define NODE_RECLAIM_PRIORITY 4
|
||
|
||
/*
|
||
* Percentage of pages in a zone that must be unmapped for node_reclaim to
|
||
* occur.
|
||
*/
|
||
int sysctl_min_unmapped_ratio = 1;
|
||
|
||
/*
|
||
* If the number of slab pages in a zone grows beyond this percentage then
|
||
* slab reclaim needs to occur.
|
||
*/
|
||
int sysctl_min_slab_ratio = 5;
|
||
|
||
static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat)
|
||
{
|
||
unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED);
|
||
unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) +
|
||
node_page_state(pgdat, NR_ACTIVE_FILE);
|
||
|
||
/*
|
||
* It's possible for there to be more file mapped pages than
|
||
* accounted for by the pages on the file LRU lists because
|
||
* tmpfs pages accounted for as ANON can also be FILE_MAPPED
|
||
*/
|
||
return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0;
|
||
}
|
||
|
||
/* Work out how many page cache pages we can reclaim in this reclaim_mode */
|
||
static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat)
|
||
{
|
||
unsigned long nr_pagecache_reclaimable;
|
||
unsigned long delta = 0;
|
||
|
||
/*
|
||
* If RECLAIM_UNMAP is set, then all file pages are considered
|
||
* potentially reclaimable. Otherwise, we have to worry about
|
||
* pages like swapcache and node_unmapped_file_pages() provides
|
||
* a better estimate
|
||
*/
|
||
if (node_reclaim_mode & RECLAIM_UNMAP)
|
||
nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES);
|
||
else
|
||
nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat);
|
||
|
||
/* If we can't clean pages, remove dirty pages from consideration */
|
||
if (!(node_reclaim_mode & RECLAIM_WRITE))
|
||
delta += node_page_state(pgdat, NR_FILE_DIRTY);
|
||
|
||
/* Watch for any possible underflows due to delta */
|
||
if (unlikely(delta > nr_pagecache_reclaimable))
|
||
delta = nr_pagecache_reclaimable;
|
||
|
||
return nr_pagecache_reclaimable - delta;
|
||
}
|
||
|
||
/*
|
||
* Try to free up some pages from this node through reclaim.
|
||
*/
|
||
static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
|
||
{
|
||
/* Minimum pages needed in order to stay on node */
|
||
const unsigned long nr_pages = 1 << order;
|
||
struct task_struct *p = current;
|
||
unsigned int noreclaim_flag;
|
||
struct scan_control sc = {
|
||
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
|
||
.gfp_mask = current_gfp_context(gfp_mask),
|
||
.order = order,
|
||
.priority = NODE_RECLAIM_PRIORITY,
|
||
.may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE),
|
||
.may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP),
|
||
.may_swap = 1,
|
||
.reclaim_idx = gfp_zone(gfp_mask),
|
||
};
|
||
unsigned long pflags;
|
||
|
||
trace_mm_vmscan_node_reclaim_begin(pgdat->node_id, order,
|
||
sc.gfp_mask);
|
||
|
||
cond_resched();
|
||
psi_memstall_enter(&pflags);
|
||
delayacct_freepages_start();
|
||
fs_reclaim_acquire(sc.gfp_mask);
|
||
/*
|
||
* We need to be able to allocate from the reserves for RECLAIM_UNMAP
|
||
*/
|
||
noreclaim_flag = memalloc_noreclaim_save();
|
||
set_task_reclaim_state(p, &sc.reclaim_state);
|
||
|
||
if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages ||
|
||
node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B) > pgdat->min_slab_pages) {
|
||
/*
|
||
* Free memory by calling shrink node with increasing
|
||
* priorities until we have enough memory freed.
|
||
*/
|
||
do {
|
||
shrink_node(pgdat, &sc);
|
||
} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
|
||
}
|
||
|
||
set_task_reclaim_state(p, NULL);
|
||
memalloc_noreclaim_restore(noreclaim_flag);
|
||
fs_reclaim_release(sc.gfp_mask);
|
||
psi_memstall_leave(&pflags);
|
||
delayacct_freepages_end();
|
||
|
||
trace_mm_vmscan_node_reclaim_end(sc.nr_reclaimed);
|
||
|
||
return sc.nr_reclaimed >= nr_pages;
|
||
}
|
||
|
||
int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
|
||
{
|
||
int ret;
|
||
|
||
/*
|
||
* Node reclaim reclaims unmapped file backed pages and
|
||
* slab pages if we are over the defined limits.
|
||
*
|
||
* A small portion of unmapped file backed pages is needed for
|
||
* file I/O otherwise pages read by file I/O will be immediately
|
||
* thrown out if the node is overallocated. So we do not reclaim
|
||
* if less than a specified percentage of the node is used by
|
||
* unmapped file backed pages.
|
||
*/
|
||
if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages &&
|
||
node_page_state_pages(pgdat, NR_SLAB_RECLAIMABLE_B) <=
|
||
pgdat->min_slab_pages)
|
||
return NODE_RECLAIM_FULL;
|
||
|
||
/*
|
||
* Do not scan if the allocation should not be delayed.
|
||
*/
|
||
if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC))
|
||
return NODE_RECLAIM_NOSCAN;
|
||
|
||
/*
|
||
* Only run node reclaim on the local node or on nodes that do not
|
||
* have associated processors. This will favor the local processor
|
||
* over remote processors and spread off node memory allocations
|
||
* as wide as possible.
|
||
*/
|
||
if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id())
|
||
return NODE_RECLAIM_NOSCAN;
|
||
|
||
if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags))
|
||
return NODE_RECLAIM_NOSCAN;
|
||
|
||
ret = __node_reclaim(pgdat, gfp_mask, order);
|
||
clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags);
|
||
|
||
if (!ret)
|
||
count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
|
||
|
||
return ret;
|
||
}
|
||
#endif
|
||
|
||
/**
|
||
* check_move_unevictable_folios - Move evictable folios to appropriate zone
|
||
* lru list
|
||
* @fbatch: Batch of lru folios to check.
|
||
*
|
||
* Checks folios for evictability, if an evictable folio is in the unevictable
|
||
* lru list, moves it to the appropriate evictable lru list. This function
|
||
* should be only used for lru folios.
|
||
*/
|
||
void check_move_unevictable_folios(struct folio_batch *fbatch)
|
||
{
|
||
struct lruvec *lruvec = NULL;
|
||
int pgscanned = 0;
|
||
int pgrescued = 0;
|
||
int i;
|
||
|
||
for (i = 0; i < fbatch->nr; i++) {
|
||
struct folio *folio = fbatch->folios[i];
|
||
int nr_pages = folio_nr_pages(folio);
|
||
|
||
pgscanned += nr_pages;
|
||
|
||
/* block memcg migration while the folio moves between lrus */
|
||
if (!folio_test_clear_lru(folio))
|
||
continue;
|
||
|
||
lruvec = folio_lruvec_relock_irq(folio, lruvec);
|
||
if (folio_evictable(folio) && folio_test_unevictable(folio)) {
|
||
lruvec_del_folio(lruvec, folio);
|
||
folio_clear_unevictable(folio);
|
||
lruvec_add_folio(lruvec, folio);
|
||
pgrescued += nr_pages;
|
||
}
|
||
folio_set_lru(folio);
|
||
}
|
||
|
||
if (lruvec) {
|
||
__count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
|
||
__count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
|
||
unlock_page_lruvec_irq(lruvec);
|
||
} else if (pgscanned) {
|
||
count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
|
||
}
|
||
}
|
||
EXPORT_SYMBOL_GPL(check_move_unevictable_folios);
|