The patch titled
Subject: mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()
has been added to the -mm tree. Its filename is
mm-page-writebackc-fix-divide-by-zero-in-bdi_dirty_limits.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page-writebackc-fix-divide-by-zero-in-bdi_dirty_limits.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page-writebackc-fix-divide-by-zero-in-bdi_dirty_limits.patch
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From: Maxim Patlasov <MPatlasov@xxxxxxxxxxxxx>
Subject: mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()
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@xxxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN mm/page-writeback.c~mm-page-writebackc-fix-divide-by-zero-in-bdi_dirty_limits mm/page-writeback.c
--- a/mm/page-writeback.c~mm-page-writebackc-fix-divide-by-zero-in-bdi_dirty_limits
+++ a/mm/page-writeback.c
@@ -1306,9 +1306,9 @@ static inline void bdi_dirty_limits(stru
*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
_
Patches currently in -mm which might be from MPatlasov@xxxxxxxxxxxxx are
mm-page-writebackc-fix-divide-by-zero-in-bdi_dirty_limits.patch
mm-add-strictlimit-knob-v2.patch
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