linux-kernel - Re: [PATCH] clockevent: don't remove broadcast device when cpu is dead

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Date:	Tue, 12 Jan 2010 20:28:27 -0500
From:	Marc Dionne <marc.c.dionne@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Xiaotian Feng <dfeng@...hat.com>, linux-kernel@...r.kernel.org,
	Magnus Damm <damm@...l.co.jp>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>
Subject: Re: [PATCH] clockevent: don't remove broadcast device when cpu is 
	dead

On Tue, Jan 12, 2010 at 8:20 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Thu, 7 Jan 2010, Xiaotian Feng wrote:
>
>> Marc reported BUG during shutdown, after debugging, kernel is trying
>> to remove a broadcast device which mode is CLOCK_EVT_MODE_ONESHOT.
>>
>> The root cause for this bug is that in clockevents_notify,
>> "cpumask_weight(dev->cpumask) == 1" is always true even if dev is a
>
> Why is cpumask_weight(dev->cpumask) == 1 always true when we shutdown
> a non boot cpu ?
>
> The broadcast device is not a per cpu device and the cpumask should
> not only contain the CPU which is shut down !
>
> The patch is papering over the real problem.
>
> Marc, can you please apply the following debug patch and provide the
> dmesg outputs from boot and shutdown ?
>
> Thanks,
>
>        tglx

Full dmesg output from boot is attached.

On shutdown I wrote down the message just before the BUG by hand
(after modifying your patch a little to let it BUG):

CE Remove ffffffff81a44100 hpet bc: 1

Marc

Download attachment "boot_ce" of type "application/octet-stream" (44188 bytes)