This is a note to let you know that I've just added the patch titled
mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()
to the 3.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-page-writeback.c-fix-divide-by-zero-in-bdi_dirty_limits.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f6789593d5cea42a4ecb1cbeab6a23ade5ebbba7 Mon Sep 17 00:00:00 2001
From: Maxim Patlasov <MPatlasov@xxxxxxxxxxxxx>
Date: Wed, 30 Jul 2014 16:08:21 -0700
Subject: mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()
From: Maxim Patlasov <MPatlasov@xxxxxxxxxxxxx>
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@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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1324,9 +1324,9 @@ 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 stable-queue which might be from MPatlasov@xxxxxxxxxxxxx are
queue-3.15/mm-page-writeback.c-fix-divide-by-zero-in-bdi_dirty_limits.patch
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