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Date: Thu, 10 Oct 2013 08:41:18 -0700
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: Anatol Pomozov <anatol.pomozov@...il.com>,
Jens Axboe <axboe@...nel.dk>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 030/104] cfq: explicitly use 64bit divide operation for 64bit arguments
3.8.13.11 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Anatol Pomozov <anatol.pomozov@...il.com>
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@...il.com>
Acked-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
block/cfq-iosched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index e62e920..1a872282 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1484,7 +1484,7 @@ static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
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;
--
1.8.1.2
--
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