linux-kernel - Re: Mysterious CFQ crash and RCU

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Message-ID: <4DDD51A6.1030509@fusionio.com>
Date:	Wed, 25 May 2011 20:59:50 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	Paul Bolle <pebolle@...cali.nl>
CC:	"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: Mysterious CFQ crash and RCU

On 2011-05-25 19:28, Paul Bolle wrote:
> On Wed, 2011-05-25 at 10:46 +0200, Jens Axboe wrote:
>> I don't think we are dealing with bad RCU usage in CFQ. My gut tells me
>> that this is related to the merging of cooperating queues. It fits
>> roughly with the time frame of when this issue started occuring, and
>> some of that reference logic looks fragile/racy.
>>
>> So if you _can_ test a patch easily, please try this one. It'll disable
>> that logic.
> 
> I'm sorry, but with that patch (adapted to out previous discussion, so
> simply returning NULL) applied I still hit the same Oops:

No worries, it's still a data point. Back to the drawing board...

-- 
Jens Axboe

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