Re: [-mm] warning during suspend [was: suspend race -mm regression]

[Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>]

Suresh Siddha wrote:
> On Thu, 2009-09-10 at 13:57 -0700, Andrew Morton wrote:
>> On Sat, 05 Sep 2009 22:41:37 +0800
>> Xiao Guangrong <ericxiao.gr@gmail.com> wrote:
>>
>>> Jiri Slaby ______:
>>>> On 09/05/2009 12:36 AM, Jiri Slaby wrote:
>>>>> On 09/05/2009 12:30 AM, Jiri Slaby wrote:
>>>>>> WARNING: at kernel/smp.c:124
>>>>>> __generic_smp_call_function_interrupt+0xfd/0x110()
>>>>>> Hardware name: To Be Filled By O.E.M.
>>>>>> Modules linked in: nfs lockd auth_rpcgss sunrpc ath5k ath
>>>>>> Pid: 3423, comm: pm-suspend Not tainted 2.6.31-rc8-mm1_64 #762
>>>>>> Call Trace:
>>>>>>  [<ffffffff8103fc48>] warn_slowpath_common+0x78/0xb0
>>>>>>  [<ffffffff8103fc8f>] warn_slowpath_null+0xf/0x20
>>>>>>  [<ffffffff8106950d>] __generic_smp_call_function_interrupt+0xfd/0x110
>>>>>>  [<ffffffff8106956a>] hotplug_cfd+0x4a/0xa0
>>>>>>  [<ffffffff81434e47>] notifier_call_chain+0x47/0x90
>>>>>>  [<ffffffff8105b311>] raw_notifier_call_chain+0x11/0x20
>>>>>>  [<ffffffff8141ece0>] _cpu_down+0x150/0x2d0
>>>>> It's the CPU_DEAD notifier:
>>>>> ffffffff8141ecd0:       48 83 ce 07             or     $0x7,%rsi
>>>>> ffffffff8141ecd4:       48 c7 c7 08 ff 5d 81    mov
>>>>> $0xffffffff815dff08,%rdi
>>>>> ffffffff8141ecdb:       e8 20 c6 c3 ff          callq  ffffffff8105b300
>>>>> <raw_notifier_call_chain>
>>>>> ffffffff8141ece0:       3d 02 80 00 00          cmp    $0x8002,%eax
>>>> And it's due to:
>>>> generic-ipi-fix-the-race-between-generic_smp_call_function_-and-hotplug_cfd.patch
>>>>
>>> I think it has collision between my patch and below patch:
> 
> Xiao, I am not sure if the race that you are trying to fix here indeed
> exists. Doesn't the stop machine that we do as part of cpu down address
> and avoid the race that you mention? Have you seen any real crashes and
> hangs or is it theory?
> 

Suresh, please see my explanation in another mail, see below URL:
http://marc.info/?l=linux-kernel&m=125265516529139&w=2

Thanks,
Xiao