linux-kernel - Re: [RFC] [PATCH 2/2] cgroups: make procs file writable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <AANLkTimrJFiidM8BlUNvmzfapUAv8369R9PYnTscasEf@mail.gmail.com>
Date:	Wed, 2 Jun 2010 13:31:41 -0700
From:	Paul Menage <menage@...gle.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ben Blum <bblum@...rew.cmu.edu>, linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, akpm@...ux-foundation.org,
	ebiederm@...ssion.com, lizf@...fujitsu.com, matthltc@...ibm.com
Subject: Re: [RFC] [PATCH 2/2] cgroups: make procs file writable

On Wed, Jun 2, 2010 at 1:20 PM, Oleg Nesterov <oleg@...hat.com> wrote:
>
> Yes sure. The main thread can exit via sys_exit(), this doesn't affect
> the thread group. Of course, I am not saying this is common practice,
> perhaps no "important" app does this.

This check has been in cgroups for quite a while and no-one's
complained so far...

> But I still can't understand why we can't just remove it. Both
> cgroup_attach_task() and cgroup_attach_proc() should handle the
> possible races correctly anyway.

The "it" that you're proposing to remove is in fact the code that
handles those races.

Anyway, I think this issue is orthogonal to the movability of entire
processes - with Ben's patch, an exited-but-not-reaped group leader is
immovable either via "tasks" or "cgroup.procs". Changing the race
condition handling to allow such movement would be a separate issue.

Paul

Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/