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Date: Fri, 20 Mar 2009 19:36:42 +0100
From: Ingo Molnar <mingo@elte.hu>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, LKML <linux-kernel@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <peterz@infradead.org>,
       Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH 0/5] [GIT PULL] updates for tip/tracing/ftrace
Message-ID: <20090320183642.GA2070@elte.hu>
References: <20090318031423.981603258@goodmis.org> <20090318055924.GA24627@elte.hu> <20090318073903.GA31341@elte.hu> <20090319073357.GA14615@elte.hu> <alpine.DEB.2.00.0903191309170.16987@gandalf.stny.rr.com> <20090320174331.GH6698@linux.vnet.ibm.com>
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* Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:

> On Thu, Mar 19, 2009 at 01:21:47PM -0400, Steven Rostedt wrote:
> > 
> > I'm still not able to reproduce, but...
> > 
> > On Thu, 19 Mar 2009, Ingo Molnar wrote:
> > 
> > > * Ingo Molnar <mingo@elte.hu> wrote:
> > > 
> > > > these latest ftrace changes caused a lockup on a -tip testsystem:
> > > 
> > > Note, even with Rusty's offstack-cpumask fix applied (in latest 
> > > -tip), i can reproduce a lockup:
> > > 
> 
> [ . . . ]
> 
> > This looks like it is RCU/stop_machine related. The CPU is stuck in
> > in stop_machine? I see that rcu_torture is running. Does this go away if 
> > you turn off rcu_torture?
> 
> Grasping at straws...  Does Lai's rcu_barrier() fix help?

which one is that?

	Ingo