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Date: Sun, 07 Oct 2012 22:35:01 +0530
From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
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To: "Kirill A. Shutemov" <kirill@shutemov.name>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, Dipankar Sarma <dipankar@in.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Steffen Klassert <steffen.klassert@secunet.com>,
        linux-crypto@vger.kernel.org,
        "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Subject: Re: Deadlock on poweroff
References: <20121007024711.GA21403@shutemov.name> <20121007160311.GE2485@linux.vnet.ibm.com> <20121007165012.GA23535@shutemov.name>
In-Reply-To: <20121007165012.GA23535@shutemov.name>
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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