linux-kernel - Re: Random panic in load

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Message-ID: <53D0B358.5010400@daenzer.net>
Date:	Thu, 24 Jul 2014 16:18:48 +0900
From:	Michel Dänzer <michel@...nzer.net>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Random panic in load_balance() with 3.16-rc

On 23.07.2014 18:31, Michel Dänzer wrote:
> On 23.07.2014 18:25, Peter Zijlstra wrote:
>> On Wed, Jul 23, 2014 at 10:28:19AM +0200, Peter Zijlstra wrote:
>>
>>> Of course, the other thing that patch did is clear sgp->power (now
>>> sgc->capacity). 
>>
>> Hmm, re-reading the thread there isn't a clear confirmation its this
>> patch at all. Could you perhaps bisect this to either verify it is
>> indeed that patch we're talking about:
>>
>> caffcdd8d27b ("sched: Do not zero sg->cpumask and sg->sgp->power in build_sched_groups()")
>>
>> or find which patch is causing this.
> 
> It can take a long time for the problem to occur, so I need to run at
> least for one or two days to be at least somewhat sure a given kernel is
> not affected.
> 
> I'll try reproducing the problem with your previous suggestions first,

Just happened again, with your robustness patch and setting
sg->sgc->capacity = 0.

> but if I manage to do that, I guess there's no alternative to bisecting...

I hope the assembly output I sent earlier helps, I'm afraid bisecting
this could be painful.


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer
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