The patch titled
Subject: mm/ksm: Handle protnone saved writes when making page write protect
has been added to the -mm tree. Its filename is
mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect.patch
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------------------------------------------------------
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Subject: mm/ksm: Handle protnone saved writes when making page write protect
Without this KSM will consider the page write protected, but a numa fault can
later mark the page writable. This can result in memory corruption.
Link: http://lkml.kernel.org/r/1487498625-10891-3-git-send-email-aneesh.kumar@xxxxxxxxxxxxxxxxxx
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
index b6f3a8a4b738..8c8ba48bef0b 100644
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/pgtable.h | 8 ++++++++
mm/ksm.c | 9 +++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff -puN include/asm-generic/pgtable.h~mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect include/asm-generic/pgtable.h
--- a/include/asm-generic/pgtable.h~mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect
+++ a/include/asm-generic/pgtable.h
@@ -233,6 +233,10 @@ static inline void ptep_set_wrprotect(st
#define pte_mk_savedwrite pte_mkwrite
#endif
+#ifndef pte_clear_savedwrite
+#define pte_clear_savedwrite pte_wrprotect
+#endif
+
#ifndef pmd_savedwrite
#define pmd_savedwrite pmd_write
#endif
@@ -241,6 +245,10 @@ static inline void ptep_set_wrprotect(st
#define pmd_mk_savedwrite pmd_mkwrite
#endif
+#ifndef pmd_clear_savedwrite
+#define pmd_clear_savedwrite pmd_wrprotect
+#endif
+
#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
diff -puN mm/ksm.c~mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect mm/ksm.c
--- a/mm/ksm.c~mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect
+++ a/mm/ksm.c
@@ -880,7 +880,8 @@ static int write_protect_page(struct vm_
if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
goto out_unlock;
- if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
+ if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) ||
+ (pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte))) {
pte_t entry;
swapped = PageSwapCache(page);
@@ -905,7 +906,11 @@ static int write_protect_page(struct vm_
}
if (pte_dirty(entry))
set_page_dirty(page);
- entry = pte_mkclean(pte_wrprotect(entry));
+
+ if (pte_protnone(entry))
+ entry = pte_mkclean(pte_clear_savedwrite(entry));
+ else
+ entry = pte_mkclean(pte_wrprotect(entry));
set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);
}
*orig_pte = *pvmw.pte;
_
Patches currently in -mm which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
mm-autonuma-dont-use-set_pte_at-when-updating-protnone-ptes.patch
mm-autonuma-let-architecture-override-how-the-write-bit-should-be-stashed-in-a-protnone-pte.patch
mm-autonuma-let-architecture-override-how-the-write-bit-should-be-stashed-in-a-protnone-pte-v3.patch
mm-ksm-handle-protnone-saved-writes-when-making-page-write-protect.patch
powerpc-mm-autonuma-switch-ppc64-to-its-own-implementeation-of-saved-write.patch
powerpc-mm-autonuma-switch-ppc64-to-its-own-implementeation-of-saved-write-v3.patch
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