From: Frank Mayhar <fmayhar@google.com>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: Crash in elevator_dispatch_fn() (e.g. deadline_dispatch()) when changing elevators.
Date: Wed, 22 Jan 2014 07:46:58 -0800 [thread overview]
Message-ID: <1390405618.20232.42.camel@bobble.lax.corp.google.com> (raw)
In-Reply-To: <1390319905.20232.38.camel@bobble.lax.corp.google.com>
On Tue, 2014-01-21 at 07:58 -0800, Frank Mayhar wrote:
> Replacing? Or adding to? Is BYPASS always set when DYING is set? (My
> guess is not but I haven't done an exhaustive analysis.) So the
> relevant code snippet in __elv_next_request() would be:
> if (unlikely(blk_queue_dying(q)) ||
> unlikely(blk_queue_bypass(q)) ||
> !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
> return NULL;
FYI, I've made this change and tested it. I can't say for certain that
it fixes the crash (since it's one of those races that's difficult to
reproduce), but it does seem to pass all the tests I've thrown at it so
far.
--
Frank Mayhar
310-460-4042
next prev parent reply other threads:[~2014-01-22 15:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1389995976.20232.27.camel@bobble.lax.corp.google.com>
[not found] ` <20140118143145.GD3640@htj.dyndns.org>
2014-01-21 15:58 ` Crash in elevator_dispatch_fn() (e.g. deadline_dispatch()) when changing elevators Frank Mayhar
2014-01-22 15:46 ` Frank Mayhar [this message]
2014-01-23 18:38 ` Frank Mayhar
2014-01-23 18:56 ` Tejun Heo
2014-01-23 21:14 ` Frank Mayhar
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