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Message-ID: <b647ffbd0807020150y650c3172me64b70710a8158d7@mail.gmail.com>
Date: Wed, 2 Jul 2008 10:50:34 +0200
From: "Dmitry Adamushko" <dmitry.adamushko@gmail.com>
To: "Lai Jiangshan" <laijs@cn.fujitsu.com>
Subject: Re: [BUG] CFS vs cpu hotplug
Cc: "Ingo Molnar" <mingo@elte.hu>,
       "Heiko Carstens" <heiko.carstens@de.ibm.com>,
       "Peter Zijlstra" <a.p.zijlstra@chello.nl>,
       "Avi Kivity" <avi@qumranet.com>, linux-kernel@vger.kernel.org,
       "Andrew Morton" <akpm@linux-foundation.org>
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2008/7/2 Lai Jiangshan <laijs@cn.fujitsu.com>:
> Ingo Molnar wrote:
>> * Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
>>
>>> The following oops still occurred whether this patch is applied or not.
>>
>>>  [<ffffffff8059372c>] notifier_call_chain+0x33/0x5b
>>>  [<ffffffff802476a9>] __raw_notifier_call_chain+0x9/0xb
>>>  [<ffffffff802476ba>] raw_notifier_call_chain+0xf/0x11
>>>  [<ffffffff805736d6>] _cpu_down+0x191/0x256
>>>  [<ffffffff805737c1>] cpu_down+0x26/0x36
>>>  [<ffffffff805749c1>] store_online+0x32/0x75
>>>  [<ffffffff803d1982>] sysdev_store+0x24/0x26
>>>  [<ffffffff802d2551>] sysfs_write_file+0xe0/0x11c
>>>  [<ffffffff80290e6b>] vfs_write+0xae/0x137
>>>  [<ffffffff802913d3>] sys_write+0x47/0x70
>>>  [<ffffffff8020b1eb>] system_call_after_swapgs+0x7b/0x80
>>
>> hm, there were multiple problems in this area and a lot of dormant bugs.
>> Do you have this recent upstream commit in your tree:
> Hi, Ingo
>        I tested it again with the most recent upstreams(including the
> following patch) committed, the oops still occurred.

[ taken from the oops ]
>
> kernel BUG at kernel/sched.c:6133!
>

is it BUG_ON(rq->nr_running != 0); in your sched.c?

hum, it's line #6134 in the recent sched.c version. So with the recent
version it was "kernel BUG at kernel/sched.c:6134!" right?

could you please try to get a crash with my additional debugging patch
(you may find it in this thread) applied?
We should see then all tasks that have been migrated (or failed to be
migrated) during migration_call(CPU_DEAD, ...).

TIA,

-- 
Best regards,
Dmitry Adamushko
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