From: "Lina Lu" <lulina_nuaa@foxmail.com>
To: "Vivek Goyal" <vgoyal@redhat.com>
Cc: "linux kernel mailing list" <linux-kernel@vger.kernel.org>
Subject: Re: Re: cfq-iosched.c: panic in cfq_dispatch_requests
Date: Tue, 22 Mar 2011 23:32:47 +0800 [thread overview]
Message-ID: <201103222332465003523@foxmail.com> (raw)
In-Reply-To: 201103201523220468314@foxmail.com
On 2011-03-21 22:08:19, Vivek Goyal wrote:
>On Sun, Mar 20, 2011 at 03:23:23PM +0800, Lina Lu wrote:
>> Hi Vivek,
>>
>> I did some test with blkio weight policy these days. The kernel panic
>> once in a while.
>>
>> From the calltrace, It 's in func cfq_dispatch_requests(+0x058D).
>> And I caught a divide by zero error with system monitor tools.
>
>Hi Lina,
>
>Can you please paste the full backtrace here.
>
>>
>> The panic happens when I first set 100 weight to two IO pids, then
>> change the weight to 200, and begin to perform IO. The kernel panic
>> accurately when the IO begin.
>
>So you notice this only if weights are changed otherwise not?
Hi Vivek
Thanks for this patch! I did objdump and find place that divide by zero.
It's in cfq_group_slice function, the st->total_weight is zero in my issue.
As described in the patch, this is because I change the weight when the
group on service tree.
Thanks
Lina
>
>Recently Justin fixed a bug in CFQ where crash can happen when weights
>are changed. This fix in Jens's block tree. Can you please apply this
>patch and see if it resolves your issue too.
>
>commit 8184f93eced1e304721c2a55c00d87d5a14f8907
>Author: Justin TerAvest <teravest@google.com>
>Date: Thu Mar 17 16:12:36 2011 +0100
>
> cfq-iosched: Don't update group weights when on service tree
>
>Thanks
>Vivek
@
next prev parent reply other threads:[~2011-03-22 15:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-20 7:23 cfq-iosched.c: panic in cfq_dispatch_requests Lina Lu
2011-03-21 14:07 ` Vivek Goyal
2011-03-22 15:32 ` Lina Lu [this message]
2011-03-22 15:39 ` Vivek Goyal
2011-03-22 15:48 ` Lina Lu
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