linux-kernel - Re: workqueue code needing preemption disabled

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Message-ID: <1363626487.25967.186.camel@gandalf.local.home>
Date:	Mon, 18 Mar 2013 13:08:07 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	RT <linux-rt-users@...r.kernel.org>,
	Clark Williams <clark@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: workqueue code needing preemption disabled

On Mon, 2013-03-18 at 09:43 -0700, Tejun Heo wrote:

> Making gcwq locks disable preemption would be much safer / easier, but
> if that's not desirable, anything touching gcwq->idle_list would be a
> good place to start - worker_enter_idle() and worker_leave_idle().
> Hmmm... ignoring CPU hotplug, I think those two might just do it.
> Give it a try?  How reproducible is the problem?

Not very :-( I triggered it twice on a 40 CPU box. It can go
approximately 1 month before it triggers. And the box we are testing on
is currently a loaner, and we have it on extension right now. Which
means we wont have it much longer.

But perhaps that's the place to fix things.

Thanks,

-- Steve


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