Re: [PATCH] blk-mq: Fix recently introduced races in the timeout handling code

[Tejun Heo <tj@kernel.org>]

Hello, Sagi.

On Mon, Apr 09, 2018 at 11:37:15AM +0300, Sagi Grimberg wrote:
> 
> >If a completion occurs after blk_mq_rq_timed_out() has reset
> >rq->aborted_gstate and the request is again in flight when the timeout
> >expires then a request will be completed twice: a first time by the
> >timeout handler and a second time when the regular completion occurs.
> >
> >Additionally, the blk-mq timeout handling code ignores completions that
> >occur after blk_mq_check_expired() has been called and before
> >blk_mq_rq_timed_out() has reset rq->aborted_gstate. If a block driver
> >timeout handler always returns BLK_EH_RESET_TIMER then the result will
> >be that the request never terminates.
> 
> OK, now I understand how we can complete twice. Israel, can you verify
> this patch solves your double completion problem?
> 
> Given that it is, the change log of your patches should be modified to
> the original bug report it solves.
> 
> Thread starts here:
> http://lists.infradead.org/pipermail/linux-nvme/2018-February/015848.html

Can you please see whether the following two patches fix the problem
you've been seeing?

 http://lkml.kernel.org/r/20180402190053.GC388343@devbig577.frc2.facebook.com
 http://lkml.kernel.org/r/20180402190120.GD388343@devbig577.frc2.facebook.com

Thanks.

-- 
tejun