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Date:   Wed, 28 Nov 2018 15:42:31 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     =?iso-8859-1?Q?J=FCrg?= Billeter <j@bitron.ch>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Andy Lutomirski <luto@kernel.org>, linux-api@vger.kernel.org,
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Subject: Re: [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT
Message-ID: <20181128144230.GG30395@redhat.com>
References: <20181127225408.7553-1-j@bitron.ch>
 <20181127225408.7553-2-j@bitron.ch>
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On 11/27, Jürg Billeter wrote:
>
> @@ -704,6 +713,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
>  	struct task_struct *p, *n;
>  	LIST_HEAD(dead);
>  
> +	if (group_dead && tsk->signal->kill_descendants_on_exit)
> +		walk_process_tree(tsk, kill_descendant_visitor, NULL);

Well, this is not exactly right, at least this is suboptimal in that
other sub-threads can too call walk_process_tree(kill_descendant_visitor)
later for no reason.