linux-kernel - Re: cfq: oops in __call_for_each

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Message-ID: <4C61E7B1.1090607@kernel.dk>
Date:	Tue, 10 Aug 2010 19:58:41 -0400
From:	Jens Axboe <axboe@...nel.dk>
To:	Jeff Layton <jlayton@...hat.com>
CC:	Jeff Moyer <jmoyer@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: cfq: oops in __call_for_each_cic

On 08/10/2010 12:35 PM, Jeff Layton wrote:
> On Tue, 10 Aug 2010 12:10:05 -0400
> Jens Axboe <axboe@...nel.dk> wrote:
> 
>> On 08/10/2010 10:27 AM, Jeff Layton wrote:
>>> On Tue, 10 Aug 2010 10:22:41 -0400
>>> Jeff Moyer <jmoyer@...hat.com> wrote:
>>>
>>>> Jeff Layton <jlayton@...hat.com> writes:
>>>>
>>>>> Saw this oops on my test machine this morning. I rebooted the machine
>>>>> last night and hadn't done anything on it other than log in this
>>>>> morning. The kernel here is based on Steve French's git tree, which is
>>>>> based on Linus' as of Sunday Aug 8th. Last non-cifs commit is:
>>>>
>>>> This looks a lot like this bug:
>>>>   https://bugzilla.redhat.com/show_bug.cgi?id=577968
>>>>
>>>> See also:
>>>>   http://kerneloops.org/guilty.php?guilty=cfq_free_io_context&version=2.6.34-rc&start=2228224&end=2260991&class=oops
>>>>
>>>> It's been around since 2.6.30.8 according to kerneloops.org.  If you
>>>> find that you have a reliable way of reproducing the issue, that would
>>>> be great.
>>>>
>>>
>>> Ok, thanks -- no clear reproducer so far. This morning was the
>>> first time I've seen it and it was on the console of my rawhide
>>> machine. The last thing I did with it was reboot it last night. I
>>> suspect that the gzip process came from a cron job or something.
>>
>> What version did you hit it on?
>>
> 
> It was a kernel built out of git, based on Steve French's git tree. The
> last commit from Linus in it was
> 45d7f32c7a43cbb9592886d38190e379e2eb2226. Everything else on top of
> that was patches that only touched cifs code. cifs.ko hadn't been
> plugged in since it was rebooted.

OK. That bug is pretty elusive, so far I haven't been able to figure
out what the heck is going on here and my attempts at reproducing
have all failed. The reports so far seem to have the cron component
in common. Does fedora ionice some cron jobs or anything like that?
Or use CLONE_IO?

-- 
Jens Axboe

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