From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Dominique Martinet <dominique.martinet@cea.fr>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
V9FS Developers <v9fs-developer@lists.sourceforge.net>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race
Date: Mon, 4 Jan 2016 16:59:15 +0100 [thread overview]
Message-ID: <20160104155915.GI6344@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CALCETrW5bz0jmx+NP_UJGdVmHdPS_-hzTecRrec-Ed+8RY=tgQ@mail.gmail.com>
On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote:
> [add cc's]
>
> Hi scheduler people:
>
> This is relatively easy for me to reproduce. Any hints for debugging
> it? Could we really have a bug in which processes that are
> schedulable as a result of mutex unlock aren't always reliably
> scheduled?
I would expect that to cause wide-spread fail, then again, virt is known
to tickle timing issues that are improbable on actual hardware so
anything is possible.
Does it reproduce with DEBUG_MUTEXES set? (I'm not seeing a .config
here).
If its really easy you could start by tracing events/sched/sched_switch
events/sched/sched_wakeup, those would be the actual scheduling events.
Without DEBUG_MUTEXES there's the MUTEX_SPIN_ON_OWNER code that could
still confuse things, but that's mutex internal and not scheduler
related.
If it ends up being the SPIN_ON_OWNER bits we'll have to cook up some
extra debug patches.
next prev parent reply other threads:[~2016-01-04 15:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-04 5:52 Hang triggered by udev coldplug, looks like a race Andy Lutomirski
2015-12-07 19:18 ` Andy Lutomirski
2015-12-07 22:46 ` [V9fs-developer] " Dominique Martinet
2015-12-08 1:59 ` Andy Lutomirski
2015-12-08 2:33 ` Al Viro
2015-12-08 22:49 ` Andy Lutomirski
2015-12-09 6:23 ` Dominique Martinet
2015-12-09 6:41 ` Dominique Martinet
2015-12-09 6:45 ` Al Viro
2015-12-17 21:06 ` Andy Lutomirski
2015-12-24 10:51 ` Dominique Martinet
2015-12-30 6:43 ` Andy Lutomirski
2016-01-04 15:59 ` Peter Zijlstra [this message]
2016-01-04 16:09 ` Dominique Martinet
2016-01-04 19:07 ` Andy Lutomirski
2016-01-04 19:27 ` Peter Zijlstra
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