From: Mike Snitzer <snitzer@redhat.com>
To: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
device-mapper development <dm-devel@redhat.com>,
"hch@lst.de" <hch@lst.de>
Subject: Re: [PATCH 8/9] dm: Fix two race conditions related to stopping and starting queues
Date: Thu, 1 Sep 2016 18:18:23 -0400 [thread overview]
Message-ID: <20160901221823.GA13209@redhat.com> (raw)
In-Reply-To: <20160901211718.GA12894@redhat.com>
On Thu, Sep 01 2016 at 5:17pm -0400,
Mike Snitzer <snitzer@redhat.com> wrote:
> On Thu, Sep 01 2016 at 4:52pm -0400,
> Bart Van Assche <bart.vanassche@sandisk.com> wrote:
>
> > On 09/01/2016 01:48 PM, Mike Snitzer wrote:
> > >Yeah, I since fixed that. Doesn't change the fact that your use of
> > >blk_mq_freeze_queue() causes the 100% cpu usage.
> >
> > Hello Mike,
> >
> > Sorry but that doesn't make sense to me. blk_mq_freeze_queue()
> > either returns quickly or waits. It cannot cause 100% CPU usage.
> > Something else must be going on. If you can make the code available
> > that you used in your test I will have a look at it.
>
> The suspend is hanging due the blk_mq_freeze_queue() -- and in turn the
> resume (after reinstating paths) never happens. So no paths are
> available. IO just keeps getting requeued, hence the 100% usage.
>
> The root of the problem is that the suspend isn't completing though.
>
> I've moved your work out to my private devel branch, see:
> http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=devel
FYI I get the same 'dmsetup suspend --nolockfs --noflush mp' hang,
running mptest's test_02_sdev_delete, when I try your unmodified
patchset, see:
http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=devel.bart
next prev parent reply other threads:[~2016-09-01 22:18 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-31 22:14 [PATCH 0/9] dm patches for kernel v4.9 Bart Van Assche
2016-08-31 22:15 ` [PATCH 1/9] blk-mq: Introduce blk_mq_queue_stopped() Bart Van Assche
2016-08-31 22:16 ` [PATCH 2/9] dm: Rename a function argument Bart Van Assche
2016-09-01 3:29 ` Mike Snitzer
2016-09-01 14:17 ` Bart Van Assche
2016-08-31 22:16 ` [PATCH 3/9] dm: Introduce signal_pending_state() Bart Van Assche
2016-08-31 22:16 ` [PATCH 4/9] dm: Convert wait loops Bart Van Assche
2016-08-31 22:17 ` [PATCH 5/9] dm: Add two lockdep_assert_held() statements Bart Van Assche
2016-08-31 22:17 ` [PATCH 6/9] dm: Simplify dm_old_stop_queue() Bart Van Assche
2016-08-31 22:17 ` [PATCH 7/9] dm: Mark block layer queue dead before destroying the dm device Bart Van Assche
2016-08-31 22:18 ` [PATCH 8/9] dm: Fix two race conditions related to stopping and starting queues Bart Van Assche
2016-09-01 3:13 ` Mike Snitzer
2016-09-01 14:23 ` Bart Van Assche
2016-09-01 15:05 ` Mike Snitzer
2016-09-01 15:31 ` Bart Van Assche
2016-09-01 15:50 ` Mike Snitzer
2016-09-01 16:12 ` Mike Snitzer
2016-09-01 17:59 ` Bart Van Assche
2016-09-01 19:05 ` Mike Snitzer
2016-09-01 19:35 ` Mike Snitzer
2016-09-01 20:15 ` Bart Van Assche
2016-09-01 20:33 ` Mike Snitzer
2016-09-01 20:39 ` Bart Van Assche
2016-09-01 20:48 ` Mike Snitzer
2016-09-01 20:52 ` Bart Van Assche
2016-09-01 21:17 ` Mike Snitzer
2016-09-01 22:18 ` Mike Snitzer [this message]
2016-09-01 22:22 ` Bart Van Assche
2016-09-01 22:26 ` Mike Snitzer
2016-09-01 23:17 ` Bart Van Assche
2016-09-01 23:47 ` Mike Snitzer
2016-09-02 0:03 ` Bart Van Assche
2016-09-02 15:12 ` Mike Snitzer
2016-09-02 16:10 ` should blk-mq halt requeue processing while queue is frozen? [was: Re: [PATCH 8/9] dm: Fix two race conditions related to stopping and starting queues] Mike Snitzer
2016-09-02 22:42 ` [dm-devel] should blk-mq halt requeue processing while queue is frozen? Bart Van Assche
2016-09-02 22:42 ` Bart Van Assche
2016-09-03 0:34 ` Mike Snitzer
2016-09-07 16:41 ` Mike Snitzer
2016-09-13 8:01 ` [dm-devel] " Bart Van Assche
2016-09-13 14:36 ` Mike Snitzer
2016-08-31 22:18 ` [PATCH 9/9] dm path selector: Avoid that device removal triggers an infinite loop Bart Van Assche
2016-09-01 2:49 ` Mike Snitzer
2016-09-01 14:14 ` Bart Van Assche
2016-09-01 15:06 ` Mike Snitzer
2016-09-01 15:22 ` Bart Van Assche
2016-09-01 15:26 ` Mike Snitzer
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