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
78 lines
2.6 KiB
Diff
78 lines
2.6 KiB
Diff
From 361de9fb44163c4e693022786af380a2b2298c6d Mon Sep 17 00:00:00 2001
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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
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Date: Fri, 24 Feb 2017 14:59:19 -0800
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Subject: [PATCH 4/4] mm/ksm: handle protnone saved writes when making page
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write protect
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Without this KSM will consider the page write protected, but a numa
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fault can later mark the page writable. This can result in memory
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corruption.
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Link: http://lkml.kernel.org/r/1487498625-10891-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com
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Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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(backported from commit 595cd8f256d24face93b2722927ec9c980419c26)
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Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
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---
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include/asm-generic/pgtable.h | 8 ++++++++
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mm/ksm.c | 9 +++++++--
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2 files changed, 15 insertions(+), 2 deletions(-)
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diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
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index b6f3a8a4b738..8c8ba48bef0b 100644
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--- a/include/asm-generic/pgtable.h
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+++ b/include/asm-generic/pgtable.h
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@@ -200,6 +200,10 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
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#define pte_mk_savedwrite pte_mkwrite
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#endif
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+#ifndef pte_clear_savedwrite
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+#define pte_clear_savedwrite pte_wrprotect
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+#endif
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+
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#ifndef pmd_savedwrite
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#define pmd_savedwrite pmd_write
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#endif
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@@ -208,6 +212,10 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
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#define pmd_mk_savedwrite pmd_mkwrite
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#endif
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+#ifndef pmd_clear_savedwrite
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+#define pmd_clear_savedwrite pmd_wrprotect
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+#endif
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+
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#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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static inline void pmdp_set_wrprotect(struct mm_struct *mm,
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diff --git a/mm/ksm.c b/mm/ksm.c
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index fed4afd8293b..099dfa45d596 100644
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--- a/mm/ksm.c
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+++ b/mm/ksm.c
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@@ -878,7 +878,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
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if (!ptep)
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goto out_mn;
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- if (pte_write(*ptep) || pte_dirty(*ptep)) {
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+ if (pte_write(*ptep) || pte_dirty(*ptep) ||
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+ (pte_protnone(*ptep) && pte_savedwrite(*ptep))) {
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pte_t entry;
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swapped = PageSwapCache(page);
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@@ -903,7 +904,11 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
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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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+
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+ if (pte_protnone(entry))
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+ entry = pte_mkclean(pte_clear_savedwrite(entry));
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+ else
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+ entry = pte_mkclean(pte_wrprotect(entry));
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set_pte_at_notify(mm, addr, ptep, entry);
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}
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*orig_pte = *ptep;
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--
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2.7.4
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