vmscan: fix shrinker callback bug in fs/super.c
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>
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 790651b..a83833a 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -20,6 +20,7 @@
* '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.