This is a note to let you know that I've just added the patch titled
cfq: explicitly use 64bit divide operation for 64bit arguments
to the 3.11-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:
cfq-explicitly-use-64bit-divide-operation-for-64bit-arguments.patch
and it can be found in the queue-3.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f3cff25f05f2ac29b2ee355e611b0657482f6f1d Mon Sep 17 00:00:00 2001
From: Anatol Pomozov <anatol.pomozov@xxxxxxxxx>
Date: Sun, 22 Sep 2013 12:43:47 -0600
Subject: cfq: explicitly use 64bit divide operation for 64bit arguments
From: Anatol Pomozov <anatol.pomozov@xxxxxxxxx>
commit f3cff25f05f2ac29b2ee355e611b0657482f6f1d upstream.
'samples' is 64bit operant, but do_div() second parameter is 32.
do_div silently truncates high 32 bits and calculated result
is invalid.
In case if low 32bit of 'samples' are zeros then do_div() produces
kernel crash.
Signed-off-by: Anatol Pomozov <anatol.pomozov@xxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Cc: Jonghwan Choi <jhbird.choi@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/cfq-iosched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1803,7 +1803,7 @@ static u64 cfqg_prfill_avg_queue_size(st
if (samples) {
v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
- do_div(v, samples);
+ v = div64_u64(v, samples);
}
__blkg_prfill_u64(sf, pd, v);
return 0;
Patches currently in stable-queue which might be from anatol.pomozov@xxxxxxxxx are
queue-3.11/cfq-explicitly-use-64bit-divide-operation-for-64bit-arguments.patch
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