Re: [PATCH 3/3] blk-mq: Fix the queue freezing mechanism

From: Tejun Heo
Date: Thu Sep 24 2015 - 14:14:39 EST


Hello,

On Thu, Sep 24, 2015 at 11:09:33AM -0700, Bart Van Assche wrote:
> On 09/24/2015 10:49 AM, Tejun Heo wrote:
> > Again, that doesn't happen.
>
> Hello Tejun,
>
> In case anyone would be interested, the backtraces for the lockup I had
> observed are as follows:

If this is happening and it's not caused by a hung in-flight request,
it's either percpu_ref being buggy or the forementioned kill/reinit
race screwing it up. percpu_ref_kill() is expected to disable
tryget_live() in a finite amount of time regardless of concurrent
tryget tries.

Thanks.

--
tejun
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