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| author | Maxim Patlasov <MPatlasov@parallels.com> | 2014-07-30 16:08:21 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-08-07 14:52:37 -0700 |
| commit | c05d1fe6c19f4df2f0b8cba151a8f0c53b87d878 (patch) | |
| tree | dd563a33f99503bf3765f3b27f41aca4371521f4 | |
| parent | 45bb13558a17336d0c90ce093653019a3c5d8daf (diff) | |
| download | lwn-c05d1fe6c19f4df2f0b8cba151a8f0c53b87d878.tar.gz lwn-c05d1fe6c19f4df2f0b8cba151a8f0c53b87d878.zip | |
mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()
commit f6789593d5cea42a4ecb1cbeab6a23ade5ebbba7 upstream.
Under memory pressure, it is possible for dirty_thresh, calculated by
global_dirty_limits() in balance_dirty_pages(), to equal zero. Then, if
strictlimit is true, bdi_dirty_limits() tries to resolve the proportion:
bdi_bg_thresh : bdi_thresh = background_thresh : dirty_thresh
by dividing by zero.
Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
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>
| -rw-r--r-- | mm/page-writeback.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d013dba21429..9f45f87a5859 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1324,9 +1324,9 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi, *bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); if (bdi_bg_thresh) - *bdi_bg_thresh = div_u64((u64)*bdi_thresh * - background_thresh, - dirty_thresh); + *bdi_bg_thresh = dirty_thresh ? div_u64((u64)*bdi_thresh * + background_thresh, + dirty_thresh) : 0; /* * In order to avoid the stacked BDI deadlock we need |