From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [patch 1/4] Ignore stolen time in the softlockup watchdog
Date: Tue, 24 Apr 2007 13:24:24 -0700
Message-ID: <462E6778.7070305@goop.org>
References: <20070327214919.800272641@goop.org>	<20070327215827.871954359@goop.org>	<20070423234910.50149faf.akpm@linux-foundation.org>	<462E43A7.1050001@goop.org>	<20070424105738.e0ce36a9.akpm@linux-foundation.org>	<462E4969.6070802@goop.org>	<20070424113222.ed2e1314.akpm@linux-foundation.org>
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To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Prarit Bhargava <prarit@redhat.com>, Rick Lindsley <ricklind@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, john stultz <johnstul@us.ibm.com>, Linux Kernel <linux-kernel@vger.kernel.org>, Eric Dumazet <dada1@cosmosbay.com>, virtualization@lists.osdl.org, Chris Lalancette <clalance@redhat.com>, Paul Mackerras <paulus@samba.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>
List-Id: virtualization@lists.linuxfoundation.org

Jeremy Fitzhardinge wrote:
> Andrew Morton wrote:
>   
>> Well, it _is_ mysterious.
>>
>> Did you try to locate the code which failed?  I got lost in macros and
>> include files, and gave up very very easily.  Stop hiding, Ingo.
>>   
>>     
>
> OK, I've managed to reproduce it.  Removing the local_irq_save/restore
> from sched_clock() makes it go away, as I'd expect (otherwise it would
> really be magic).  But given that it never seems to touch the softlockup
> during testing, I have no idea what difference it makes...

And sched_clock's use of local_irq_save/restore appears to be absolutely
correct, so I think it must be triggering a bug in either the self-tests
or lockdep itself.

The only way I could actually extract the test code itself was to run
the whole thing through cpp+indent, but it doesn't shed much light.

It's also not clear to me if there are 6 independent failures, or if
they're a cascade.

    J