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Date: Wed, 22 Jan 2014 12:44:43 +0100
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Dipankar Sarma <dipankar@in.ibm.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@kernel.org>
Subject: Re: [Bisected] qemu hangs on current git
Message-ID: <20140122114443.GA389@x4>
References: <20140121215119.GA389@x4>
 <20140122085035.GA390@x4>
 <20140122093755.GA388@x4>
 <20140122102435.GH31570@twins.programming.kicks-ass.net>
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On 2014.01.22 at 11:24 +0100, Peter Zijlstra wrote:
> On Wed, Jan 22, 2014 at 10:37:55AM +0100, Markus Trippelsdorf wrote:
> > git bisect points to:
> > 
> > commit 8cb75e0c4ec9786b81439761eac1d18d4a931af3
> > Author: Peter Zijlstra <peterz@infradead.org>
> > Date:   Wed Nov 20 12:22:37 2013 +0100
> > 
> >     sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding
> > 
> 
> No idea why kvm would go funny on that, real hardware runs fine.
> 
> You're running a !PREEMPT kernel, right? Does the below make any
> difference?

Yes: CONFIG_PREEMPT_VOLUNTARY=y 
And yes, your patch fixes the issue.
Thanks.

-- 
Markus