linux-kernel - Re: Deadlock on poweroff

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Message-ID: <5071B63D.4020300@linux.vnet.ibm.com>
Date:	Sun, 07 Oct 2012 22:35:01 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
CC:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, Dipankar Sarma <dipankar@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Steffen Klassert <steffen.klassert@...unet.com>,
	linux-crypto@...r.kernel.org,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: Re: Deadlock on poweroff

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

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