From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marc.Zyngier@arm.com (Marc Zyngier)
Date: Thu, 26 May 2011 17:20:23 +0100
Subject: [BUG] "sched: Remove rq->lock from the first half of ttwu()"
	locks up on ARM
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	<1306409575.1200.71.camel@twins> <1306412511.1200.90.camel@twins>
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To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, 2011-05-26 at 18:09 +0200, Peter Zijlstra wrote:
> On Thu, 2011-05-26 at 17:59 +0200, Peter Zijlstra wrote:
> > On Thu, 2011-05-26 at 17:45 +0200, Oleg Nesterov wrote:
> > > Stupid question. Can't we fix this problem if we do
> > > 
> > >         -       if (p == current)
> > >         +       if (cpu == raw_smp_processor_id())
> > > 
> > > ?
> > > 
> > > I forgot the rules... but iirc task_cpu(p) can't be changed under us?
> > 
> > Easy enough to test.. brain gave out again,. hold on ;-)
> 
> The below seems to run all-right so far, I'll let it run for a while.

Doesn't look very good here. The serial console basically locks up as
soon as the system gets busy, even if the kernel compilation seem to
progress at a decent pace.

	M.

-- 
Reality is an implementation detail.