Re: [BUG] CFS vs cpu hotplug

[Lai Jiangshan <laijs@cn.fujitsu.com>]

Dmitry Adamushko wrote:
> 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?
yes, I had test it twice yesterday, applied/not applied
your patch(no debugging).
> 
> 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?
yes, and applied your's and Zhang's patch as Ingo's advice.
> 
> 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, ...).
>
Thank you. I'll test it again with your debugging patch applied
and get more info.
> TIA,
>