3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Feiner <[email protected]>

commit dbab31aa2ceec2d201966fa0b552f151310ba5f4 upstream.

This fixes the same bug as b43790eedd31 ("mm: softdirty: don't forget to
save file map softdiry bit on unmap") and 9aed8614af5a ("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 <[email protected]>
Acked-by: Cyrill Gorcunov <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Jamie Liu <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 mm/memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1125,7 +1125,7 @@ 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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