From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 5/7][v8] zap_pid_ns_process() should use force_sig()
Date: Thu, 19 Feb 2009 19:59:54 +0100
Message-ID: <20090219185954.GB374@redhat.com>
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To: Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>, Containers <containers-qjLDD68F18O7TbgM5vRIOg@public.gmane.org>, roland-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org
List-Id: containers.vger.kernel.org

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.