From: Mike Snitzer <snitzer@redhat.com>
To: Bart Van Assche <Bart.VanAssche@sandisk.com>
Cc: device-mapper development <dm-devel@redhat.com>
Subject: Re: [PATCH 9/9] dm path selector: Avoid that device removal triggers an infinite loop
Date: Thu, 1 Sep 2016 11:06:42 -0400 [thread overview]
Message-ID: <20160901150642.GB11074@redhat.com> (raw)
In-Reply-To: <BLUPR02MB1683AC1B30C6E1EAE953C67081E20@BLUPR02MB1683.namprd02.prod.outlook.com>
On Thu, Sep 01 2016 at 10:14am -0400,
Bart Van Assche <Bart.VanAssche@sandisk.com> wrote:
> On 08/31/16 20:29, Mike Snitzer wrote:
> > On Wed, Aug 31 2016 at 6:18pm -0400,
> > Bart Van Assche <bart.vanassche@sandisk.com> wrote:
> >
> >> If pg_init_retries is set and a request is queued against a
> >> multipath device with all underlying block devices in the "dying"
> >> state then an infinite loop is triggered because activate_path()
> >> never succeeds and hence never calls pg_init_done(). Fix this by
> >> making ql_select_path() skip dying paths.
> >
> > Assuming DM multipath needs to be sprinkling these dying queue checks so
> > deep (which I'm not yet sold on):
> >
> > Same would be needed in service-time and round-robin right?
>
> Hello Mike,
>
> Before addressing service-time and round-robin path selectors I wanted
> to make sure that we reach agreement about how to fix the queue length
> path selector.
>
> Do you have a proposal for an alternative approach to fix the infinite
> loop that can be triggered during device removal?
I'm going to look closer now. But I'd prefer to see the "dying" state
check(s) elevated to DM muiltpath. Really would rather the path
selectors not have to worry about this state.
next prev parent reply other threads:[~2016-09-01 15:06 UTC|newest]
Thread overview: 45+ 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
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
2016-09-03 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 [this message]
2016-09-01 15:22 ` Bart Van Assche
2016-09-01 15:26 ` Mike Snitzer
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