linux-kernel - Re: [BUG 3.12.rc4] Oops: unable to handle kernel paging request during shutdown

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Date:	Mon, 28 Oct 2013 16:01:14 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Knut Petersen <Knut_Petersen@...nline.de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Greg KH <greg@...ah.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [BUG 3.12.rc4] Oops: unable to handle kernel paging request
 during shutdown


* Knut Petersen <Knut_Petersen@...nline.de> wrote:

> On 26.10.2013 13:43, Ingo Molnar wrote:
> >* Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> >
> >>On Fri, Oct 25, 2013 at 11:23 AM, Thomas Gleixner <tglx@...utronix.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
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