From mboxrd@z Thu Jan  1 00:00:00 1970
From: anton.vorontsov@linaro.org (Anton Vorontsov)
Date: Fri, 4 May 2012 18:47:14 -0700
Subject: [PATCH 1/9] cpu: Introduce clear_tasks_mm_cpumask() helper
In-Reply-To: <20120426165911.00cebd31.akpm@linux-foundation.org>
References: <20120423070641.GA27702@lizard> <20120423070736.GA30752@lizard>
 <20120426165911.00cebd31.akpm@linux-foundation.org>
Message-ID: <20120505014711.GA24566@lizard>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, Apr 26, 2012 at 04:59:11PM -0700, Andrew Morton wrote:
[...]
> > 	 so its not like new tasks will ever get this cpu set in
> > +	 * their mm mask. -- Peter Zijlstra
> > +	 * Thus, we may use rcu_read_lock() here, instead of grabbing
> > +	 * full-fledged tasklist_lock.
> > +	 */
> > +	rcu_read_lock();
> > +	for_each_process(p) {
> > +		struct task_struct *t;
> > +
> > +		t = find_lock_task_mm(p);
> > +		if (!t)
> > +			continue;
> > +		cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
> > +		task_unlock(t);
> > +	}
> > +	rcu_read_unlock();
> > +}
> 
> It is good that this code exists under CONFIG_HOTPLUG_CPU.  Did you
> check that everything works correctly with CONFIG_HOTPLUG_CPU=n?

Yeah, only the code under CONFIG_HOTPLUG_CPU calls the function, so
it should be all fine.

Thanks!

-- 
Anton Vorontsov
Email: cbouatmailru at gmail.com