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Subject: Re: 2.6.18-rt1
From: Lee Revell <rlrevell@joe-job.com>
To: dipankar@in.ibm.com
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Thomas Gleixner <tglx@linutronix.de>, John Stultz <johnstul@us.ibm.com>,
       "Paul E. McKenney" <paulmck@us.ibm.com>,
       Arjan van de Ven <arjan@infradead.org>
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References: <20060920141907.GA30765@elte.hu>
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Date: Sat, 30 Sep 2006 14:25:55 -0400
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On Sat, 2006-09-30 at 23:48 +0530, Dipankar Sarma wrote:
> On Sat, Sep 30, 2006 at 02:06:04PM -0400, Lee Revell wrote:
> > I got this Oops with -rt3, looks RCU related.  Apologies in advance if
> > it's already known.
> > 
> > Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: 
> >  [<ffffffff802aafa7>] __rcu_read_unlock+0x2e/0x82
> > PGD 46a3067 PUD 4e27067 PMD 0 
> > Oops: 0002 [1] PREEMPT SMP 
> > CPU 1 
> 
> I see a very similar crash while running rcutorture on 2.6.18-mm1 and
> my rcu patchset that has rcupreempt stuff rom -rt. I don't see this
> while running on 2.6.18-rc3, but then rc3 had an older version
> of rcutorture. I am working on narrowing it down.
> 
> The following script reproduces the problem quickly (within
> a couple of minutes) in my 4-cpu x86_64 system -

Let me know if you want more info such as config.  I was compiling a
kernel when the Oops occurred.  System is Athlon X2.

Lee

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