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authorMikulas Patocka <mpatocka@redhat.com>2011-10-31 17:08:57 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2011-11-26 09:08:40 -0800
commit26e15787b98f3cac67d0b9458befd24adbef7272 (patch)
parent1bccf76533a1e336dfa8007554d4283253e259c7 (diff)
vmscan: fix shrinker callback bug in fs/super.c
commit 09f363c7363eb10cfb4b82094bd7064e5608258b upstream. The callback must not return -1 when nr_to_scan is zero. Fix the bug in fs/super.c and add this requirement to the callback specification. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: Dave Chinner <david@fromorbit.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@suse.de>
2 files changed, 2 insertions, 1 deletions
diff --git a/fs/super.c b/fs/super.c
index 3f56a269a4f4..32a81f3467e0 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -61,7 +61,7 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
return -1;
if (!grab_super_passive(sb))
- return -1;
+ return !sc->nr_to_scan ? 0 : -1;
if (sb->s_op && sb->s_op->nr_cached_objects)
fs_objects = sb->s_op->nr_cached_objects(sb);
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 790651b4e5ba..a83833a1f7a2 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -20,6 +20,7 @@ struct shrink_control {
* 'nr_to_scan' entries and attempt to free them up. It should return
* the number of objects which remain in the cache. If it returns -1, it means
* it cannot do any scanning at this time (eg. there is a risk of deadlock).
+ * The callback must not return -1 if nr_to_scan is zero.
* The 'gfpmask' refers to the allocation we are currently trying to
* fulfil.