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From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>,
	Sodagudi Prasad <psodagud@codeaurora.org>
Cc: mingo@kernel.org, gregkh@linuxfoundation.org,
	bigeasy@linutronix.de, tglx@linutronix.de, isaacm@codeaurora.org,
	linux-kernel@vger.kernel.org
Subject: Re: cpu stopper threads and setaffinity leads to deadlock
Date: Thu, 02 Aug 2018 10:27:58 +0200	[thread overview]
Message-ID: <1533198478.11791.10.camel@gmx.de> (raw)
In-Reply-To: <20180802081252.GG2494@hirez.programming.kicks-ass.net>

On Thu, 2018-08-02 at 10:12 +0200, Peter Zijlstra wrote:
> On Wed, Aug 01, 2018 at 06:34:40PM -0700, Sodagudi Prasad wrote:
> > diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
> > index e190d1e..f932e1e 100644
> > --- a/kernel/stop_machine.c
> > +++ b/kernel/stop_machine.c
> > @@ -87,9 +87,9 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct
> > cpu_stop_work *work)
> >                 __cpu_stop_queue_work(stopper, work, &wakeq);
> >         else if (work->done)
> >                 cpu_stop_signal_done(work->done);
> > -       raw_spin_unlock_irqrestore(&stopper->lock, flags);
> > 
> >         wake_up_q(&wakeq);
> > +       raw_spin_unlock_irqrestore(&stopper->lock, flags);
> > 
> 
> That puts the wakeup back under stopper lock, which causes another
> deadlock iirc.

Yup, one you fixed.

0b26351b910fb (Peter Zijlstra 2018-04-20 11:50:05 +0200 92)     wake_up_q(&wakeq);

  reply	other threads:[~2018-08-02  8:28 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-02  1:34 cpu stopper threads and setaffinity leads to deadlock Sodagudi Prasad
2018-08-02  8:12 ` Peter Zijlstra
2018-08-02  8:27   ` Mike Galbraith [this message]
2018-08-02  8:45 ` Peter Zijlstra
2018-08-02  9:49 ` Peter Zijlstra
2018-08-03 11:41   ` Thomas Gleixner
2018-08-03 18:57     ` Sodagudi Prasad

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