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    Subject[PATCH 3.14 187/238] mm: softdirty: keep bit when zapping file pte
    Date
    3.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: Peter Feiner <pfeiner@google.com>

    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 <pfeiner@google.com>
    Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
    Cc: Pavel Emelyanov <xemul@parallels.com>
    Cc: Jamie Liu <jamieliu@google.com>
    Cc: Hugh Dickins <hughd@google.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -1120,7 +1120,7 @@ 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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