Re: [RFD] Merge task counter into memcg

[Frederic Weisbecker <fweisbec@gmail.com>]

On Tue, Apr 17, 2012 at 08:17:53AM -0700, Tejun Heo wrote:
> Hello, Frederic.
> 
> On Thu, Apr 12, 2012 at 06:59:27PM +0200, Frederic Weisbecker wrote:
> > I want:
> > 
> > a) to prevent the forkbomb from going far enough to DDOS the machine
> > b) to be able to kill that forkbomb once detected, in one go without race
> > against concurrent forks.
> > 
> > I think a) can work just fine with kernel stack limiting. I also need
> > to be notified about the fact we reached the limit. And b) should
> > be feasible with the help of the cgroup freezer. 
> 
> kmem allocation fail after reaching the limit which in turn should
> fail task creation.  Isn't that the same effect as the task_counter as
> implemented?

That's it.

> 
> > > Is there anything for which you need to know exactly the number of
> > > processes?
> > 
> > No that's really about prevent/kill forkbomb as far as I'm concerned.
> 
> Hmm... so, accounting overhead aside, if the only purpose is
> preventing the whole machine being brought down by a fork bomb, kmem
> limiting is enough, right?

I think so yeah.