From: Peter Feiner <pfeiner@xxxxxxxxxx>
Subject: mm: softdirty: keep bit when zapping file pte
Fixes the same bug as b43790eedd31e9 ("mm: softdirty: don't forget to save
file map softdiry bit on unmap") and 9aed8614af5a05cd ("mm/memory.c: don't
forget to set softdirty on file mapped fault") where the return value of
pte_*mksoft_dirty was being ignored.
To be sure that no other pte/pmd "mk" function return values were being
ignored, I annotated the functions in arch/x86/include/asm/pgtable.h with
__must_check and rebuilt.
The userspace effect of this bug is that the softdirty mark might be
lost if a file mapped pte get zapped.
Signed-off-by: Peter Feiner <pfeiner@xxxxxxxxxx>
Acked-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Jamie Liu <jamieliu@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.12+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/memory.c~mm-softdirty-keep-bit-when-zapping-file-pte mm/memory.c
--- a/mm/memory.c~mm-softdirty-keep-bit-when-zapping-file-pte
+++ a/mm/memory.c
@@ -1127,7 +1127,7 @@ again:
addr) != page->index) {
pte_t ptfile = pgoff_to_pte(page->index);
if (pte_soft_dirty(ptent))
- pte_file_mksoft_dirty(ptfile);
+ ptfile = pte_file_mksoft_dirty(ptfile);
set_pte_at(mm, addr, pte, ptfile);
}
if (PageAnon(page))
_
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