From mboxrd@z Thu Jan  1 00:00:00 1970
From: Bart Van Assche <bvanassche@acm.org>
Subject: Re: 3.15-rc4: circular locking dependency triggered by
	dm-multipath
Date: Tue, 06 May 2014 15:46:03 +0200
Message-ID: <5368E79B.8000208@acm.org>
References: <5368ABE8.9050909@acm.org> <20140506132211.GA22945@redhat.com>
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To: Mike Snitzer <snitzer@redhat.com>
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On 05/06/14 15:22, Mike Snitzer wrote:
> On Tue, May 06 2014 at  5:31am -0400,
> Bart Van Assche <bvanassche@acm.org> wrote:
>> Has anyone else perhaps already run into this ?
> 
> Not seen this, how easily is it reproduced?
> 
> These recent commits are clearly the issue:
> 
> e809917735e dm mpath: push back requests instead of queueing
> 3e9f1be1b40 dm mpath: remove process_queued_ios()
> 
> Need to take a closer look at the lockdep splat you provided.

All I did was to simulate a cable pull while running a fio test on top
of a dm-multipath device on top of a few SCSI devices. This lockdep
report was generated the first time I ran the cable pull simulation. I
have not yet tried to reproduce this but it's not impossible that this
is 100% reproducible. The same test runs fine with kernel 3.14.

Bart.