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From: David Howells <dhowells@redhat.com>
In-Reply-To: <20091210004703.232302055@linutronix.de>
References: <20091210004703.232302055@linutronix.de> <20091210001308.247025548@linutronix.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: dhowells@redhat.com, LKML <linux-kernel@vger.kernel.org>,
       "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
       Dipankar Sarma <dipankar@in.ibm.com>, Ingo Molnar <mingo@elte.hu>,
       Peter Zijlstra <peterz@infradead.org>, Oleg Nesterov <oleg@tv-sign.ru>,
       Al Viro <viro@zeniv.linux.org.uk>, James Morris <jmorris@namei.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Oleg Nesterov <oleg@redhat.com>
Subject: Re: [patch 6/9] signal: Fix racy access to __task_cred in kill_pid_info_as_uid()
Date: Fri, 11 Dec 2009 13:53:47 +0000
Message-ID: <13441.1260539627@redhat.com>
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Thomas Gleixner <tglx@linutronix.de> wrote:

> kill_pid_info_as_uid() accesses __task_cred() without being in a RCU
> read side critical section. tasklist_lock is not protecting that when
> CONFIG_TREE_PREEMPT_RCU=y.
> 
> Convert the whole tasklist_lock section to rcu and use
> lock_task_sighand to prevent the exit race.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Acked-by: David Howells <dhowells@redhat.com>