mm/backing-dev.c: fix error path in wb_init()

We need to use post-decrement to get percpu_counter_destroy() called on
&wb->stat[0].  Moreover, the pre-decremebt would cause infinite
out-of-bounds accesses if the setup code failed at i==0.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 926c76d56388d12ea723b68add1e5b7ab6613842..c554d173a65fa640186b058e5e97be68b48c7ea5 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -328,7 +328,7 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
        return 0;
 
 out_destroy_stat:
-       while (--i)
+       while (i--)
                percpu_counter_destroy(&wb->stat[i]);
        fprop_local_destroy_percpu(&wb->completions);
 out_put_cong: