mm: make sure _PAGE_SWP_SOFT_DIRTY bit is not set on present pte
_PAGE_SOFT_DIRTY bit should never be set on present pte so add VM_BUG_ON
to catch any potential future abuse.
Also add a comment on _PAGE_SWP_SOFT_DIRTY definition explaining scope of
its usage.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 8d16bef..3d19994 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -315,21 +315,6 @@
return pmd_set_flags(pmd, _PAGE_SOFT_DIRTY);
}
-static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
-{
- return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY);
-}
-
-static inline int pte_swp_soft_dirty(pte_t pte)
-{
- return pte_flags(pte) & _PAGE_SWP_SOFT_DIRTY;
-}
-
-static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
-{
- return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY);
-}
-
static inline pte_t pte_file_clear_soft_dirty(pte_t pte)
{
return pte_clear_flags(pte, _PAGE_SOFT_DIRTY);
@@ -446,6 +431,7 @@
#ifndef __ASSEMBLY__
#include <linux/mm_types.h>
+#include <linux/mmdebug.h>
#include <linux/log2.h>
static inline int pte_none(pte_t pte)
@@ -864,6 +850,24 @@
{
}
+static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
+{
+ VM_BUG_ON(pte_present(pte));
+ return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY);
+}
+
+static inline int pte_swp_soft_dirty(pte_t pte)
+{
+ VM_BUG_ON(pte_present(pte));
+ return pte_flags(pte) & _PAGE_SWP_SOFT_DIRTY;
+}
+
+static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
+{
+ VM_BUG_ON(pte_present(pte));
+ return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY);
+}
+
#include <asm-generic/pgtable.h>
#endif /* __ASSEMBLY__ */