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> 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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
