[an error occurred while processing this directive]

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: <20111207182214.GA7610@google.com>
Date:	Wed, 7 Dec 2011 10:22:14 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	paul@...lmenage.org, rjw@...k.pl, lizf@...fujitsu.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, matthltc@...ibm.com,
	akpm@...ux-foundation.org, oleg@...hat.com,
	kamezawa.hiroyu@...fujitsu.com
Subject: Re: [PATCH UPDATED 03/10] threadgroup: extend threadgroup_lock()
 to cover exit and exec

Hello, Frederic.

On Wed, Dec 07, 2011 at 04:30:54PM +0100, Frederic Weisbecker wrote:
> I don't understand what you mean. On your patches, you only process tasks
> that don't have PF_EXITING, ie: you don't include these in the flex array
> on cgroup_attach_proc(). So that still applies in my proposal.
> 
> From the exit path we would have:
> 
> 	exit_signal() {
> 		lock_threadgroup_change(task);
> 		task->flags |= PF_EXITING;
> 		lock_threadgroup(task);
> 	}
> 
> 	exit all the rest: mm, etc...
> 
> Then from cgroup_attach_proc():
> 
> 	lock_threadgroup(task);
> 	for_each_thread(task) {
> 		if (!(task->flags & PF_EXITING))
> 			include in flex array
> 	}
> 
> Am I forgetting something?

The point I was trying to make was that doing the above would make
->exit() called on dangling task of a threadgroup in rare cases.
ie. With the proposed change, after a threadgroup migration, all tasks
in the threadgroup is in the new cgroup.  No method will be called on
the old cgroup for any of the member task.  With the above change,
process migration would leave out dying tasks and ->exit() can be
called with the old cgroup.

Hmm... that said, it probably doesn't matter all that much either way.
I'll update the patchset and repost.

Thanks.

-- 
tejun
--
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/