linux-kernel - Re: 2.6.22-rc1: Broken suspend on SMP with tifm

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Message-ID: <20070513215425.GA3240@tv-sign.ru>
Date:	Mon, 14 May 2007 01:54:25 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	Alex Dubov <oakad@...oo.com>, Pierre Ossman <drzeus@...eus.cx>
Subject: Re: 2.6.22-rc1: Broken suspend on SMP with tifm

On 05/13, Rafael J. Wysocki wrote:
>
> On Sunday, 13 May 2007 23:34, Oleg Nesterov wrote:
> > On 05/13, Rafael J. Wysocki wrote:
> > >
> > > @@ -819,20 +843,31 @@ static int __devinit workqueue_cpu_callb
> > >  
> > > +
> > > +		case CPU_DEAD_FROZEN:
> > > +			if (wq->freezeable) {
> > > +				take_over_work(wq, cpu);
> > > +				thaw_process(cwq->thread);
> > 
> > Suppose that PF_NOFREEZE task T does flush_workqueue(), and CPU 1 has pending
> > works. T does flush_cpu_workqueue(0), CPU_DEAD_FROZEN moves works from CPU 1
> > to CPU 0, T does flush_cpu_workqueue(1) and finds nothing.
> 
> I don't think this is possible, because we've acquired workqueue_mutex in
> _cpu_down().

Yes, we did... but flush_workqueue() doesn't take it?

Oleg.

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