From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Pavel Emelyanov <xemul@parallels.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Tejun Heo <tj@kernel.org>, Vasiliy Kulikov <segoon@openwall.com>,
Andrew Vagin <avagin@openvz.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] fs, proc: Introduce the /proc/<pid>/children entry v2
Date: Fri, 9 Dec 2011 21:11:49 +0400 [thread overview]
Message-ID: <20111209171149.GU21678@moon> (raw)
In-Reply-To: <20111209165536.GA25268@redhat.com>
On Fri, Dec 09, 2011 at 05:55:36PM +0100, Oleg Nesterov wrote:
...
>
> To simplify, let's talk about children_seq_start() your patch adds.
> Suppose that we make ->children/sibling "rcu-safe" (we replace
> __unhash_process()->list_del_init() with list_del_rcu, and so on).
>
> Now, children_seq_start() does:
>
> rcu_read_lock();
>
> list_for_each(child, task->children)
> ...;
>
> Suppose that this task exits and reparents the child we are looking at.
> Once reparent_leader() moves it into another list, list_for_each()
> can never stop.
>
> In short. forget_original_parent() changes the _head_ of the list,
> in some sense.
>
Yeah, I missed this, my bad! Thanks for explanation, Oleg. I'll
post updated version once I finish it.
Cyrill
prev parent reply other threads:[~2011-12-09 17:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-06 18:10 [PATCH] fs, proc: Introduce the /proc/<pid>/children entry v2 Cyrill Gorcunov
2011-12-06 22:33 ` Andrew Morton
2011-12-06 22:35 ` Cyrill Gorcunov
2011-12-07 9:41 ` Cyrill Gorcunov
2011-12-07 18:27 ` Tejun Heo
2011-12-07 18:43 ` Cyrill Gorcunov
2011-12-07 18:53 ` Oleg Nesterov
2011-12-07 19:03 ` Cyrill Gorcunov
2011-12-07 19:19 ` Cyrill Gorcunov
2011-12-07 20:34 ` Cyrill Gorcunov
2011-12-07 21:52 ` Cyrill Gorcunov
2011-12-08 16:35 ` Oleg Nesterov
2011-12-08 16:50 ` Cyrill Gorcunov
2011-12-08 21:28 ` Cyrill Gorcunov
2011-12-08 21:54 ` Andrew Morton
2011-12-08 22:21 ` Cyrill Gorcunov
2011-12-09 15:30 ` Oleg Nesterov
2011-12-09 15:49 ` Cyrill Gorcunov
2011-12-09 16:55 ` Oleg Nesterov
2011-12-09 17:11 ` Cyrill Gorcunov [this message]
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