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

From: Xiao Guangrong
Date: Fri Sep 11 2009 - 03:56:02 EST




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@xxxxxxxxx> 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
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