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Date: Fri, 4 Mar 2011 21:02:42 +0800
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Subject: Re: [PATCH 05/10] block: remove per-queue plugging
From: Shaohua Li <shli@kernel.org>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <jaxboe@fusionio.com>, linux-kernel@vger.kernel.org,
        hch@infradead.org
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2011/3/4 Mike Snitzer <snitzer@redhat.com>:
> I'm now hitting a lockdep issue, while running a 'for-2.6.39/stack-plug'
> kernel, when I try an fsync heavy workload to a request-based mpath
> device (the kernel ultimately goes down in flames, I've yet to look at
> the crashdump I took)
>
>
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> [ INFO: possible circular locking dependency detected ]
> 2.6.38-rc6-snitm+ #2
> -------------------------------------------------------
> ffsb/3110 is trying to acquire lock:
> =A0(&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff811b4c4d>] flush_p=
lug_list+0xbc/0x135
>
> but task is already holding lock:
> =A0(&rq->lock){-.-.-.}, at: [<ffffffff8137132f>] schedule+0x16a/0x725
>
> which lock already depends on the new lock.
I hit this too. Can you check if attached debug patch fixes it?

Thanks,
Shaohua

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