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Date: Thu, 19 Feb 2009 19:59:54 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@osdl.org>, roland@redhat.com,
       "Eric W. Biederman" <ebiederm@xmission.com>, daniel@hozac.com,
       Containers <containers@lists.osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/7][v8] zap_pid_ns_process() should use force_sig()
Message-ID: <20090219185954.GB374@redhat.com>
References: <20090219030207.GA18783@us.ibm.com> <20090219030704.GE18990@us.ibm.com>
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On 02/18, Sukadev Bhattiprolu wrote:
>
>  	read_lock(&tasklist_lock);
>  	nr = next_pidmap(pid_ns, 1);
>  	while (nr > 0) {
> -		kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr);
> +		rcu_read_lock();
> +
> +		/*
> +		 * Use force_sig() since it clears SIGNAL_UNKILLABLE ensuring
> +		 * any nested-container's init processes don't ignore the
> +		 * signal
> +		 */
> +		task = pid_task(find_vpid(nr), PIDTYPE_PID);
> +		force_sig(SIGKILL, task);

Shouldn't we check task != NULL ?

Oleg.