Re: Deadlock on poweroff

["Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>]

On 10/07/2012 10:20 PM, Kirill A. Shutemov wrote:
> On Sun, Oct 07, 2012 at 09:03:11AM -0700, Paul E. McKenney wrote:
>> On Sun, Oct 07, 2012 at 05:47:11AM +0300, Kirill A. Shutemov wrote:
>>> Hi Paul and all,
>>>
>>> With commit 755609a9087fa983f567dc5452b2fa7b089b591f I've got deadlock on
>>> poweroff.
>>>
>>> It guess it happens because of race for cpu_hotplug.lock:
>>>
>>> 	CPU A					CPU B
>>> disable_nonboot_cpus()
>>> _cpu_down()
>>> cpu_hotplug_begin()
>>>  mutex_lock(&cpu_hotplug.lock);
>>> __cpu_notify()
>>> padata_cpu_callback()
>>> __padata_remove_cpu()
>>> padata_replace()
>>> synchronize_rcu()
>>> 					rcu_gp_kthread()
>>> 					get_online_cpus();
>>> 					mutex_lock(&cpu_hotplug.lock);
>>>
>>> Have you seen the issue before?
>>
>> This is a new one for me.  Does the following (very lightly tested)
>> patch help?
> 
> Works for me. Thanks.
> 

Could you share the patch please? Looks like it didn't hit the mailing
lists.. 

Regards,
Srivatsa S. Bhat