From: Neil Brown <neilb@suse.de>
Subject: Re: mountd randomly crash and panic the server
Date: Wed, 2 May 2007 21:29:06 +1000
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To: Gabriel Barazer <gabriel@oxeva.fr>
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In-Reply-To: message from Gabriel Barazer on Wednesday May 2
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On Wednesday May 2, gabriel@oxeva.fr wrote:
> On 05/01/2007 1:59:46 +0200, Neil Brown <neilb@suse.de> wrote:
> > 
> >>   related kernel panics, which are, I suppose, not linked to the NFS 
> >> problem (I still mention it because unrelated but linked problems like 
> >> this sometimes happens)
> > 
> > CFQ panics ?  In cfq_dispatch_insert by any chance?
> > 
> > This patch from Jens Axboe might be what you need.
> > 
> 
> The problem is exactly related to this function : Is this bug related to 
> the NFS subsystem, or am I lucky and it appears you work on the CFQ 
> scheduler as well ? :) I can test this patch, but since this bug panic() 
> the kernel, I can't afford to hang the file server very often.

I don't normally work on the CFQ scheduler, but I do work on md/raid,
and the people who had reported this bug were all using md/raid, so I
looked into it.

The patch definitely fixes the problem.

> 
> For now I have changed the scheduler to deadline with the 
> /sys/block/<device>/queue/scheduler file. Is this patch already sent to 
> the upstream kernel sources ?

Yes, it is in 2.6.21.

NeilBrown

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