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Date: Mon, 28 Oct 2013 16:01:14 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Knut Petersen <Knut_Petersen@t-online.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
        Greg KH <greg@kroah.com>, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [BUG 3.12.rc4] Oops: unable to handle kernel paging request
 during shutdown
Message-ID: <20131028150114.GA12905@gmail.com>
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* Knut Petersen <Knut_Petersen@t-online.de> wrote:

> On 26.10.2013 13:43, Ingo Molnar wrote:
> >* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> >
> >>On Fri, Oct 25, 2013 at 11:23 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> >>>Enable DEBUG_OBJECTS, DEBUG_OBJECTS_FREE, DEBUG_OBJECTS_TIMERS
> >>Yes, but nobody has actually been able to trigger it with those.
> >>It's pretty rare, and the debug options are so expensive that they
> >>aren't reasonable to enable generally...
> >>
> >>So we need to try to figure out how to trigger it, or narrow
> >>things down some way..
> >If it's timing then maybe the 1 seconds delay isn't enough
> >(especially if it's boot related, where we have a couple of delays
> >already) - the patch below triples it.
> >
> >(If the bug goes away due to some other side effect then this patch
> >won't make a difference to reproducability.)
> 
> I tried that patch, together with all the kobj debug options 
> enabled. With that kernel configuration I was unable to reproduce 
> the problem during 500 typical workload / reboot cycles. Without 
> the debug options I was able to reproduce the last reported panic 
> after 91 cycles. The debug options seem to change timing 
> sufficiently to mask the bug ;-(

Could you send me the kernel config please?

Thanks,

	Ingo