linux-kernel - Re: BUG during shutdown - bisected to commit e2912009

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Date:	Mon, 4 Jan 2010 13:43:17 -0500
From:	Marc Dionne <marc.c.dionne@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Xiaotian Feng <dfeng@...hat.com>, Ingo Molnar <mingo@...e.hu>
Subject: Re: BUG during shutdown - bisected to commit e2912009

On Fri, Jan 1, 2010 at 7:42 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Fri, 2010-01-01 at 19:27 -0500, Marc Dionne wrote:
>> I'm getting a BUG with current kernels from
>> kernel/time/clockevents.c:263 when halting the system - a restart
>> behaves normally.  I don't have a good camera handy at the moment to
>> capture the call stack on screen, but the call sequence is:
>>
>> clockevents_notify
>> hrtimer_cpu_notify
>> notifier_call_chain
>> raw_notifier_call_chain
>> _cpu_down
>> disable_nonboot_cpus
>> kernel_power_off
>> sys_reboot
>>
>> I bisected it down to commit e2912009: sched: Ensure set_task_cpu() is
>> never called on blocked tasks.  There were a few commits tested along
>> the way where I got a freeze (with the power still on) instead of a
>> BUG. Reverting that commit from the current kernel doesn't look
>> trivial, but the commit immediately preceding this one does halt fine.
>
> We somehow seem to trip up the below patch, which doesn't really make
> sense, as I can't find how task placement would affect the below error.
>
> It seems to purely test against the hot-unplugged cpu, not a cpu the
> task is running on.
>
> ---
> commit bb6eddf7676e1c1f3e637aa93c5224488d99036f
> Author: Thomas Gleixner <tglx@...utronix.de>
> Date:   Thu Dec 10 15:35:10 2009 +0100

Probably predictable but worth testing, reverting that patch does
allow my system to shutdown cleanly.

Marc
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