Re: mlockall triggred rcu_preempt stall.

From: Paul E. McKenney
Date: Tue Jul 30 2013 - 13:57:44 EST

On Fri, Jul 19, 2013 at 08:32:12PM -0400, Dave Jones wrote:
> 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.

Any news? If I don't hear otherwise, I will assume that the patch did
not help, and will therefore drop it.

Thanx, Paul

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