linux-kernel - Re: [PATCH 05/10] block: remove per-queue plugging

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Date:	Fri, 4 Mar 2011 21:02:42 +0800
From:	Shaohua Li <shli@...nel.org>
To:	Mike Snitzer <snitzer@...hat.com>
Cc:	Jens Axboe <jaxboe@...ionio.com>, linux-kernel@...r.kernel.org,
	hch@...radead.org
Subject: Re: [PATCH 05/10] block: remove per-queue plugging

2011/3/4 Mike Snitzer <snitzer@...hat.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)
>
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.38-rc6-snitm+ #2
> -------------------------------------------------------
> ffsb/3110 is trying to acquire lock:
>  (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff811b4c4d>] flush_plug_list+0xbc/0x135
>
> but task is already holding lock:
>  (&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

View attachment "stack-plug-dbg.patch" of type "text/x-patch" (1463 bytes)