linux-kernel - Re: [RFC patch 2/5] smpboot: Provide infrastructure for percpu hotplug threads

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Message-ID: <alpine.LFD.2.02.1206141817180.3086@ionos>
Date:	Thu, 14 Jun 2012 18:19:50 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [RFC patch 2/5] smpboot: Provide infrastructure for percpu
 hotplug threads

On Thu, 14 Jun 2012, Paul E. McKenney wrote:

> On Thu, Jun 14, 2012 at 07:50:38AM -0700, Paul E. McKenney wrote:
> > On Thu, Jun 14, 2012 at 03:32:19PM +0200, Thomas Gleixner wrote:
> > > On Thu, 14 Jun 2012, Paul E. McKenney wrote:
> > > > On Thu, Jun 14, 2012 at 01:20:39PM +0200, Thomas Gleixner wrote:
> > > > > I gave it a quick shot, but I was not able to reproduce the hang yet.
> > > > 
> > > > Really?  I have a strictly Western-Hemisphere bug?  ;-)
> > > 
> > > I guess I need to fire up rcu torture to make it surface.
> > 
> > A simple offline was triggering it for me.  Perhaps some of my debug
> > code was inappropriate, will retry.
> 
> And removing my debug code did the trick.  I guess some of it was really
> just bug code.  In any case, it now passes short rcutorture testing for
> me as well.
> 
> However, I do see the splat shown below.  The splat confuses me greatly,
> as I thought that this kthread should be affinitied to a single CPU and
> thus smp_processor_id() should refrain from splatting.  I don't see any
> sort of "I broke affinity" message from the scheduler.

Hmm. Is that reproducible ?
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