2b834b083d
Patches and rationale by Seth Forshee[1]: My testing shows that the "POWER9: Additional power9 patches" patches are responsible, two of them in particular: - mm: introduce page_vma_mapped_walk() - mm, ksm: convert write_protect_page() to use page_vma_mapped_walk() These patches don't appear to be included for any functionality they provide, but rather to make "mm/ksm: handle protnone saved writes when making page write protect" a clean cherry pick instead of a backport. But the backport isn't that difficult, so as far as I can tell we can do away with the other two patches. 1: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1674838/comments/108
99 lines
3.0 KiB
Diff
99 lines
3.0 KiB
Diff
From 40e1fa51bc8aa3df1d3a23711b5de62d8251bff5 Mon Sep 17 00:00:00 2001
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From: Seth Forshee <seth.forshee@canonical.com>
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Date: Wed, 3 May 2017 08:34:52 -0500
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Subject: [PATCH 2/4] Revert "mm, ksm: convert write_protect_page() to use
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page_vma_mapped_walk()"
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This reverts commit 3000e033152a70fa139765b4dbb5baec46b1cc1b.
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Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
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---
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mm/ksm.c | 34 ++++++++++++++++------------------
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1 file changed, 16 insertions(+), 18 deletions(-)
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diff --git a/mm/ksm.c b/mm/ksm.c
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index 9dd2e58fb6dc..fed4afd8293b 100644
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--- a/mm/ksm.c
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+++ b/mm/ksm.c
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@@ -856,35 +856,33 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
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pte_t *orig_pte)
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{
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struct mm_struct *mm = vma->vm_mm;
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- struct page_vma_mapped_walk pvmw = {
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- .page = page,
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- .vma = vma,
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- };
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+ unsigned long addr;
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+ pte_t *ptep;
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+ spinlock_t *ptl;
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int swapped;
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int err = -EFAULT;
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unsigned long mmun_start; /* For mmu_notifiers */
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unsigned long mmun_end; /* For mmu_notifiers */
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- pvmw.address = page_address_in_vma(page, vma);
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- if (pvmw.address == -EFAULT)
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+ addr = page_address_in_vma(page, vma);
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+ if (addr == -EFAULT)
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goto out;
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BUG_ON(PageTransCompound(page));
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- mmun_start = pvmw.address;
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- mmun_end = pvmw.address + PAGE_SIZE;
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+ mmun_start = addr;
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+ mmun_end = addr + PAGE_SIZE;
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mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
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- if (!page_vma_mapped_walk(&pvmw))
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+ ptep = page_check_address(page, mm, addr, &ptl, 0);
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+ if (!ptep)
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goto out_mn;
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- if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
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- goto out_unlock;
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- if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
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+ if (pte_write(*ptep) || pte_dirty(*ptep)) {
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pte_t entry;
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swapped = PageSwapCache(page);
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- flush_cache_page(vma, pvmw.address, page_to_pfn(page));
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+ flush_cache_page(vma, addr, page_to_pfn(page));
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/*
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* Ok this is tricky, when get_user_pages_fast() run it doesn't
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* take any lock, therefore the check that we are going to make
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@@ -894,25 +892,25 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
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* this assure us that no O_DIRECT can happen after the check
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* or in the middle of the check.
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*/
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- entry = ptep_clear_flush_notify(vma, pvmw.address, pvmw.pte);
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+ entry = ptep_clear_flush_notify(vma, addr, ptep);
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/*
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* Check that no O_DIRECT or similar I/O is in progress on the
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* page
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*/
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if (page_mapcount(page) + 1 + swapped != page_count(page)) {
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- set_pte_at(mm, pvmw.address, pvmw.pte, entry);
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+ set_pte_at(mm, addr, ptep, entry);
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goto out_unlock;
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}
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if (pte_dirty(entry))
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set_page_dirty(page);
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entry = pte_mkclean(pte_wrprotect(entry));
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- set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);
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+ set_pte_at_notify(mm, addr, ptep, entry);
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}
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- *orig_pte = *pvmw.pte;
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+ *orig_pte = *ptep;
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err = 0;
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out_unlock:
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- page_vma_mapped_walk_done(&pvmw);
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+ pte_unmap_unlock(ptep, ptl);
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out_mn:
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mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
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out:
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--
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2.7.4
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