[dm-devel] 3.15-rc4: circular locking dependency triggered by dm-multipath

[Bart Van Assche]

On 05/06/14 15:22, Mike Snitzer wrote:
> On Tue, May 06 2014 at  5:31am -0400,
> Bart Van Assche <bvanassche at 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.