linux-kernel - Re: [BUG REPORT] Kernel panic on 3.9.0-rc7-4-gbb33db7

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Date:	Fri, 19 Apr 2013 14:10:26 +0800
From:	Wanlong Gao <gaowanlong@...fujitsu.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Jens Axboe <axboe@...nel.dk>, Tejun Heo <tj@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Namhyung Kim <namhyung@...il.com>,
	Alasdair G Kergon <agk@...hat.com>,
	"dm-devel@...hat.com" <dm-devel@...hat.com>,
	Neil Brown <neilb@...e.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Wanlong Gao <gaowanlong@...fujitsu.com>
Subject: Re: [BUG REPORT] Kernel panic on 3.9.0-rc7-4-gbb33db7

On 04/19/2013 03:10 AM, Linus Torvalds wrote:
> On Thu, Apr 18, 2013 at 11:13 AM, Jens Axboe <axboe@...nel.dk> wrote:
>> On Thu, Apr 18 2013, Tejun Heo wrote:
>>> On Thu, Apr 18, 2013 at 10:39:00AM -0700, Jens Axboe wrote:
>>>>
>>>> Yep, thanks Linus for that hint... Must be someone abusing it for a
>>>> flag field post submission? Crazy.
>>>
>>> Let's hope that's not the case because there'll be blood if it is. :)
>>
>> Yeah, it's beyond the amount of crazy I've come to expect from various
>> random users of IO interfaces :-)
> 
> I think it's more likely to be some use-after-free after a long timeout.
> 
> Wanlong says it happens a few minutes after boot, so maybe something
> times out a command, does the blk_complete_request(), and free's the
> bio, which gets re-used before the softirq actually ends up running.
> 
> I note that Wanlong uses the SLAB allocator, not the SLUB one. I
> wonder if the thing goes away with SLUB, and if not, if
> CONFIG_SLUB_DEBUG_ON=y might help debug it?

Done as you mentioned, attach the config and dmesg before panic.
And the panic message almost the same as before here: https://lkml.org/lkml/2013/4/18/633

Thanks,
Wanlong Gao

> 
>                      Linus
> 


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