From: Peter Zijlstra <peterz@infradead.org>
To: Mike Galbraith <efault@gmx.de>
Cc: stable <stable@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
linux-tip-commits <linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:locking/core] sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule()
Date: Fri, 7 Oct 2016 10:29:50 +0200 [thread overview]
Message-ID: <20161007082950.GS3142@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1475804215.4075.13.camel@gmx.de>
On Fri, Oct 07, 2016 at 03:36:55AM +0200, Mike Galbraith wrote:
> Seems this may be one of those not so theoretical races. A humongous
> ppc64 box actually managed to run a task on two cores.. briefly.
Cute :-) Why was you running a year old kernel on that box anyway? ;-)
> Stable material methinks.
Yep..
> On Fri, 2015-12-04 at 03:53 -0800, tip-bot for Peter Zijlstra wrote:
> > Commit-ID: ecf7d01c229d11a44609c0067889372c91fb4f36
> > Gitweb: http://git.kernel.org/tip/ecf7d01c229d11a44609c0067889372c91fb4f36
> > Author: Peter Zijlstra <peterz@infradead.org>
> > AuthorDate: Wed, 7 Oct 2015 14:14:13 +0200
> > Committer: Ingo Molnar <mingo@kernel.org>
> > CommitDate: Fri, 4 Dec 2015 10:26:43 +0100
> >
> > sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule()
> >
> > Oleg noticed that its possible to falsely observe p->on_cpu == 0 such
> > that we'll prematurely continue with the wakeup and effectively run p on
> > two CPUs at the same time.
next prev parent reply other threads:[~2016-10-07 8:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-ecf7d01c229d11a44609c0067889372c91fb4f36@git.kernel.org>
2016-10-07 1:36 ` [tip:locking/core] sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule() Mike Galbraith
2016-10-07 6:38 ` Jiri Slaby
2016-10-07 8:29 ` Peter Zijlstra [this message]
2016-10-07 9:33 ` Mike Galbraith
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