From 24f91eba18bbfdb27e71a1aae5b3a61b67fcd091 Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Thu, 30 Jan 2014 15:46:10 -0800 Subject: [PATCH] mm: don't lose the SOFT_DIRTY flag on mprotect The SOFT_DIRTY bit shows that the content of memory was changed after a defined point in the past. mprotect() doesn't change the content of memory, so it must not change the SOFT_DIRTY bit. This bug causes a malfunction: on the first iteration all pages are dumped. On other iterations only pages with the SOFT_DIRTY bit are dumped. So if the SOFT_DIRTY bit is cleared from a page by mistake, the page is not dumped and its content will be restored incorrectly. This patch does nothing with _PAGE_SWP_SOFT_DIRTY, becase pte_modify() is called only for present pages. Fixes commit 0f8975ec4db2 ("mm: soft-dirty bits for user memory changes tracking"). Signed-off-by: Andrey Vagin Acked-by: Cyrill Gorcunov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Pavel Emelyanov Cc: Borislav Petkov Cc: Wen Congyang Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/include/asm/pgtable_types.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index a83aa44bb1fb..1aa9ccd43223 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -121,7 +121,8 @@ /* Set of bits not changed in pte_modify */ #define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ - _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY) + _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \ + _PAGE_SOFT_DIRTY) #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE) #define _PAGE_CACHE_MASK (_PAGE_PCD | _PAGE_PWT) -- 2.20.1