The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.8.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.8.3
------>
commit d693573172a1ce54f7eb7773967cb7eae30d41c2
Author: Maxim Patlasov <mpatla...@parallels.com>
Date: Wed Oct 7 15:27:55 2015 +0400
ms/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 <mpatla...@parallels.com>
Acked-by: Rik van Riel <r...@redhat.com>
Cc: Michal Hocko <mho...@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang...@intel.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
https://jira.sw.ru/browse/PSBM-40116
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
---
mm/page-writeback.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2bb28ba..429c759 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1366,9 +1366,9 @@ 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
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