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@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 6265411eb2ed..f4ca23b158b3 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -233,6 +233,10 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
 #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(struct mm_struct *mm, unsigned long addres
 #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,