From: Thomas Gleixner <tglx@linutronix.de>
To: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Jens Axboe <jaxboe@fusionio.com>,
mgalbraith@suse.com
Subject: Re: Deadlocks due to per-process plugging
Date: Thu, 12 Jul 2012 00:12:44 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1207120011070.32033@ionos> (raw)
In-Reply-To: <20120711201601.GB9779@quack.suse.cz>
On Wed, 11 Jul 2012, Jan Kara wrote:
> On Wed 11-07-12 12:05:51, Jeff Moyer wrote:
> > This eventually ends in a call to blk_run_queue_async(q) after
> > submitting the I/O from the plug list. Right? So is the question
> > really why doesn't the kblockd workqueue get scheduled?
> Ah, I didn't know this. Thanks for the hint. So in the kdump I have I can
> see requests queued in tsk->plug despite the process is sleeping in
> TASK_UNINTERRUPTIBLE state. So the only way how unplug could have been
> omitted is if tsk_is_pi_blocked() was true. Rummaging through the dump...
> indeed task has pi_blocked_on = 0xffff8802717d79c8. The dump is from an -rt
> kernel (I just didn't originally thought that makes any difference) so
> actually any mutex is rtmutex and thus tsk_is_pi_blocked() is true whenever
> we are sleeping on a mutex. So this seems like a bug in rtmutex code.
> Thomas, you seemed to have added that condition... Any idea how to avoid
> the deadlock?
Mike has sent out a fix related to the plug stuff, which I just posted
for the rt stable series. Can you verify against that ?
Thanks,
tglx
next prev parent reply other threads:[~2012-07-11 22:12 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-11 13:37 Deadlocks due to per-process plugging Jan Kara
2012-07-11 16:05 ` Jeff Moyer
2012-07-11 20:16 ` Jan Kara
2012-07-11 22:12 ` Thomas Gleixner [this message]
2012-07-12 4:12 ` Mike Galbraith
2012-07-13 12:38 ` Jan Kara
2012-07-12 2:07 ` Mike Galbraith
2012-07-12 14:15 ` Thomas Gleixner
2012-07-13 12:33 ` Jan Kara
2012-07-13 14:25 ` Thomas Gleixner
2012-07-13 14:46 ` Jan Kara
2012-07-15 8:59 ` Thomas Gleixner
2012-07-15 9:14 ` Mike Galbraith
2012-07-15 9:51 ` Thomas Gleixner
2012-07-16 2:22 ` Mike Galbraith
2012-07-16 8:59 ` Thomas Gleixner
2012-07-16 9:48 ` Mike Galbraith
2012-07-16 9:59 ` Thomas Gleixner
2012-07-16 10:13 ` Mike Galbraith
2012-07-16 10:08 ` Mike Galbraith
2012-07-16 10:19 ` Thomas Gleixner
2012-07-16 10:30 ` Mike Galbraith
2012-07-16 11:24 ` Mike Galbraith
2012-07-16 14:35 ` Mike Galbraith
2012-07-17 13:10 ` Mike Galbraith
2012-07-18 4:44 ` Mike Galbraith
2012-07-18 5:30 ` Mike Galbraith
2012-07-21 7:47 ` Mike Galbraith
2012-07-22 18:43 ` Mike Galbraith
2012-07-23 9:46 ` Mike Galbraith
2012-07-14 11:00 ` Mike Galbraith
2012-07-14 11:06 ` Mike Galbraith
2012-07-15 7:14 ` Mike Galbraith
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