linux-kernel - Re: [PATCH -mm] cgroup: Fix task counter common ancestor logic

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Message-Id: <20111109085841.ca5dfd3b.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 9 Nov 2011 08:58:41 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Ben Blum <bblum@...rew.cmu.edu>,
	Li Zefan <lizf@...fujitsu.com>,
	Paul Menage <paul@...lmenage.org>,
	Tim Hockin <thockin@...kin.org>, Tejun Heo <tj@...nel.org>,
	Containers <containers@...ts.linux-foundation.org>,
	Cgroups <cgroups@...r.kernel.org>
Subject: Re: [PATCH -mm] cgroup: Fix task counter common ancestor logic

On Tue, 8 Nov 2011 13:51:11 -0800
Andrew Morton <akpm@...ux-foundation.org> wrote:

> On Tue,  8 Nov 2011 16:21:10 +0100
> Frederic Weisbecker <fweisbec@...il.com> wrote:
> 
> > To solve this, keep the original cgroup of each thread in the thread
> > group cached in the flex array and pass it to can_attach_task()/attach_task()
> > and cancel_attach_task() so that the correct common ancestor between the old
> > and new cgroup can be safely retrieved for each task.
> 
> OK, thanks.
> 
> We need to work out what to do with this patchset.  ie: should we merge
> it.  I'm not sure that the case has been made?
> 

My impression is positive....but as other guy proposed, I feel fork-limit
should be useful, too. It allows to limit or rate-limit the number of fork().
So, I wonder some fork-limit can be implemented in this task_counter cgroup.

> Let's please drag this thing onto the table and poke at it for a while.
> Probably everyone has forgotten everything so we'll need to start
> again, sorry.  Perhaps you can (re)start proceedings by telling us why
> it's useful to our users and why we should merge it?
> 
please ;)

> 
> Some mental notes:
> 
> Tim says it would be useful for the things he's doing but doesn't
> appear to have confirmed/tested that.
> 
> Kay has said that it would not be useful for his plumber's wishlist
> item, which is a shame.
> 
> I seem to recall complaining that it doesn't address the forkbomb issue
> for non-cgroups setups, so the forkbomb issue remains unaddressed.

For non-cgroup fork-bomb, I and Minchan proposed forkbomb-killer (in 
independent way). I stop it now but if someone has interests, I
recall it from grave.

Thanks,
-Kame
 






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