linux-kernel - Re: [PATCH 2/2] pidns: find_new_reaper() can no longer switch to init_pid_ns.child

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Message-ID: <4FC74902.4070302@parallels.com>
Date:	Thu, 31 May 2012 14:33:38 +0400
From:	Pavel Emelyanov <xemul@...allels.com>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Louis Rilling <louis.rilling@...labs.com>,
	Mike Galbraith <efault@....de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] pidns: find_new_reaper() can no longer switch to
 init_pid_ns.child_reaper

On 05/30/2012 10:15 PM, Oleg Nesterov wrote:
> find_new_reaper() changes pid_ns->child_reaper, see add0d4df
> "pid_ns: zap_pid_ns_processes: fix the ->child_reaper changing".
> 
> The original reason has gone away after the previous patch,
> ->children list must be empty after zap_pid_ns_processes().
> 
> However now we can not switch to init_pid_ns.child_reaper.
> __unhash_process() relies on the "->child_reaper == parent"
> check, but this check does not work if the last exiting task
> is also the child reaper.
> 
> As Eric sugested, we can change __unhash_process() to use the
> parent's pid_ns and remove this code.
> 
> Also, with this change we can move detach_pid(PIDTYPE_PID) back,
> where it was before the previous fix.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Acked-by: Pavel Emelyanov <xemul@...allels.com>

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