migrate: don't account swapcache as shmem
authorAndrea Arcangeli <aarcange@redhat.com>
Thu, 16 Jun 2011 19:56:19 +0000 (12:56 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 16 Jun 2011 22:01:24 +0000 (15:01 -0700)
swapcache will reach the below code path in migrate_page_move_mapping,
and swapcache is accounted as NR_FILE_PAGES but it's not accounted as
NR_SHMEM.

Hugh pointed out we must use PageSwapCache instead of comparing
mapping to &swapper_space, to avoid build failure with CONFIG_SWAP=n.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/migrate.c

index e4a5c912983df5352d701bce82fb691160c2e657..666e4e677414e6d790de715761e395116441e6c4 100644 (file)
@@ -288,7 +288,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
         */
        __dec_zone_page_state(page, NR_FILE_PAGES);
        __inc_zone_page_state(newpage, NR_FILE_PAGES);
-       if (PageSwapBacked(page)) {
+       if (!PageSwapCache(page) && PageSwapBacked(page)) {
                __dec_zone_page_state(page, NR_SHMEM);
                __inc_zone_page_state(newpage, NR_SHMEM);
        }