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Subject: Re: [PATCH v2.1 01/10] cpu: Introduce clear_tasks_mm_cpumask() helper
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 26 Mar 2012 09:59:06 +0200
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Cc: Mike Frysinger <vapier@gentoo.org>,
 user-mode-linux-devel@lists.sourceforge.net, linux-sh@vger.kernel.org,
 Richard Weinberger <richard@nod.at>, linux-kernel@vger.kernel.org,
 uclinux-dist-devel@blackfin.uclinux.org, linux-mm@kvack.org,
 Anton Vorontsov <anton.vorontsov@linaro.org>, Paul Mundt <lethal@linux-sh.org>,
 John Stultz <john.stultz@linaro.org>,
 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
 Russell King <linux@arm.linux.org.uk>,
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On Sun, 2012-03-25 at 19:42 +0200, Oleg Nesterov wrote:
> __cpu_disable() is called by __stop_machine(), we know that nobody
> can preempt us and other CPUs can do nothing.=20

It would be very good to not rely on that though, I would love to get
rid of the stop_machine usage in cpu hotplug some day.