Date: Wed, 8 Feb 2012 17:46:36 -0800 (PST)
From: David Rientjes <rientjes@google.com>
To: Anton Vorontsov <anton.vorontsov@linaro.org>
cc: Oleg Nesterov <oleg@redhat.com>, Greg KH <gregkh@linuxfoundation.org>,
        KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Paul Mundt <lethal@linux-sh.org>,
        Russell King <linux@arm.linux.org.uk>,
        Mike Frysinger <vapier@gentoo.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Richard Weinberger <richard@nod.at>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/8] arm: Fix possible race on task->mm
In-Reply-To: <20120207065004.GC1496@oksana.dev.rtsoft.ru>
Message-ID: <alpine.DEB.2.00.1202081746250.31205@chino.kir.corp.google.com>
References: <20120207064809.GA29061@oksana.dev.rtsoft.ru> <20120207065004.GC1496@oksana.dev.rtsoft.ru>
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On Tue, 7 Feb 2012, Anton Vorontsov wrote:

> Checking for task->mm is dangerous as ->mm might disappear (exit_mm()
> assigns NULL under task_lock(), so tasklist lock is not enough).
> 
> We can't use get_task_mm()/mmput() pair as mmput() might sleep,
> so let's take the task lock while we care about its mm.
> 
> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

Acked-by: David Rientjes <rientjes@google.com>
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