From: hch@infradead.org (Christoph Hellwig)
Subject: [PATCH] NVMe: Fix possible scheduling while atomic error
Date: Fri, 27 May 2016 00:40:20 -0700 [thread overview]
Message-ID: <20160527074020.GB950@infradead.org> (raw)
In-Reply-To: <20160525175736.GB28668@localhost.localdomain>
On Wed, May 25, 2016@01:57:37PM -0400, Keith Busch wrote:
> > > On Tue, May 24, 2016@11:43:21AM -0700, Ming Lin wrote:
> > > >
> > > > It's blk_mq_cancel_requeue_work() that potentially sleeps.
> > >
> > > Right, I don't know what I was thinking...
> > >
> > > AFAICT, the patch is fine as-is if Christoph is okay with it.
> >
> > I still don't why we need to delay the call to blk_mq_stop_hw_queues
> > to ->queue_rq.
>
> Eh? It's still stopped in the same place as always, so it's not
> delayed. We just call it again from queue_rq because requeue_work can
> start h/w queues on its own. This is very similar to scsi's queue_rq
> in scsi_lib.c.
The rationale in SCSI is that we stop the queue when we are above
the hosts or targets queuing limit, and only I/O ocmpletions will
wake it up again. Kicking of the sotpped queues in blk_mq_requeue_work
is SCSI specific behavior that leaked into the core, and it's my fault..
Well' let's get the fix in as-is for now, but I really need to sort
this out properly, so maybe add some comments.
>
> _______________________________________________
> Linux-nvme mailing list
> Linux-nvme at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-nvme
---end quoted text---
next prev parent reply other threads:[~2016-05-27 7:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-17 21:37 [PATCH] NVMe: Fix possible scheduling while atomic error Keith Busch
2016-05-23 10:58 ` Christoph Hellwig
2016-05-23 13:41 ` Keith Busch
2016-05-23 14:36 ` Christoph Hellwig
2016-05-23 14:55 ` Keith Busch
2016-05-24 18:43 ` Ming Lin
2016-05-24 19:59 ` Keith Busch
2016-05-25 8:18 ` Christoph Hellwig
2016-05-25 17:57 ` Keith Busch
2016-05-27 7:40 ` Christoph Hellwig [this message]
2016-06-08 11:17 ` Sagi Grimberg
2016-06-08 14:43 ` Keith Busch
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