From: Steven Rostedt <rostedt@goodmis.org>
To: Mike Galbraith <efault@gmx.de>
Cc: Chris Mason <chris.mason@fusionio.com>,
"Chris L. Mason" <clmason@fusionio.com>,
"linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: 3.4.4-rt13: btrfs + xfstests 006 = BOOM.. and a bonus rt_mutex deadlock report for absolutely free!
Date: Mon, 16 Jul 2012 13:03:15 -0400 [thread overview]
Message-ID: <1342458195.2783.5.camel@acer.local.home> (raw)
In-Reply-To: <1342456567.7659.97.camel@marge.simpson.net>
On Mon, 2012-07-16 at 18:36 +0200, Mike Galbraith wrote:
>
> > > Ouch, you just turned the rt_read_lock() into a spin lock. If a higher
> > > priority process preempted a lower priority process that holds the same
> > > lock, it will deadlock.
> >
> > Hm, how, it's doing cpu_chill()?
>
> 'course PI is toast, so *poof*. Since just enabling the lockdep bits
> seems to fix it up, maybe that's the patchlet to submit (less is more).
There's that too. But the issue I was talking about is with all trylock
loops. As holding an rt-mutex now disables migration, if a high priority
process preempts a task that holds the lock, and then the high prio task
starts spinning waiting for that lock to release, the lower priority
process will never get to run to release it. The cpu_chill() doesn't
help.
-- Steve
next prev parent reply other threads:[~2012-07-16 17:03 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-12 5:47 3.4.4-rt13: btrfs + xfstests 006 = BOOM.. and a bonus rt_mutex deadlock report for absolutely free! Mike Galbraith
2012-07-12 8:44 ` Mike Galbraith
2012-07-12 9:53 ` Mike Galbraith
2012-07-12 11:43 ` Thomas Gleixner
2012-07-12 11:57 ` Mike Galbraith
2012-07-12 13:31 ` Thomas Gleixner
2012-07-12 13:37 ` Mike Galbraith
2012-07-12 13:43 ` Thomas Gleixner
2012-07-12 13:48 ` Mike Galbraith
2012-07-12 13:51 ` Mike Galbraith
2012-07-13 6:31 ` Mike Galbraith
2012-07-13 9:52 ` Thomas Gleixner
2012-07-13 10:14 ` Mike Galbraith
2012-07-13 10:26 ` Thomas Gleixner
2012-07-13 10:47 ` Chris Mason
2012-07-13 12:50 ` Mike Galbraith
2012-07-12 11:07 ` Thomas Gleixner
2012-07-12 17:09 ` Chris Mason
2012-07-13 10:04 ` Thomas Gleixner
2012-07-13 12:50 ` Chris Mason
2012-07-13 14:47 ` Thomas Gleixner
2012-07-14 10:14 ` Mike Galbraith
2012-07-15 17:56 ` Chris Mason
2012-07-16 2:02 ` Mike Galbraith
2012-07-16 16:02 ` Steven Rostedt
2012-07-16 16:26 ` Mike Galbraith
2012-07-16 16:35 ` Chris Mason
2012-07-16 16:36 ` Mike Galbraith
2012-07-16 17:03 ` Steven Rostedt [this message]
2012-07-17 4:18 ` Mike Galbraith
2012-07-17 4:27 ` Steven Rostedt
2012-07-17 4:34 ` Steven Rostedt
2012-07-17 4:46 ` Mike Galbraith
2012-07-17 4:44 ` Mike Galbraith
2012-07-17 12:54 ` Mike Galbraith
2012-07-16 10:55 ` Mike Galbraith
2012-07-16 15:43 ` Chris Mason
2012-07-16 16:16 ` Mike Galbraith
2012-07-14 13:38 ` Mike Galbraith
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