linux-kernel - Re: mlockall triggred rcu

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Message-ID: <20130720003212.GA31308@redhat.com>
Date:	Fri, 19 Jul 2013 20:32:12 -0400
From:	Dave Jones <davej@...hat.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	kosaki.motohiro@...il.com, walken@...gle.com,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org
Subject: Re: mlockall triggred rcu_preempt stall.

On Fri, Jul 19, 2013 at 03:15:39PM -0700, Paul E. McKenney wrote:
 > On Fri, Jul 19, 2013 at 10:53:23AM -0400, Dave Jones wrote:
 > > My fuzz tester keeps hitting this. Every instance shows the non-irq stack
 > > came in from mlockall.  I'm only seeing this on one box, but that has more
 > > ram (8gb) than my other machines, which might explain it.
 > 
 > Are you building CONFIG_PREEMPT=n?  I don't see any preemption points in
 > do_mlockall(), so a range containing enough vmas might well stall the
 > CPU in that case.  

That was with full preempt.

 > Does the patch below help?  If so, we probably need others, but let's
 > first see if this one helps.  ;-)

I'll try it on Monday.

	Dave

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