Re: Protection against container fork bombs [WAS: Re: memcg with kmem limit doesn't recover after disk i/o causes limit to be hit]

[Serge Hallyn <serge.hallyn@ubuntu.com>]

Quoting Dwight Engen (dwight.engen@oracle.com):
> On Wed, 23 Apr 2014 09:07:28 +0300
> Marian Marinov <mm@yuhu.biz> wrote:
> 
> > On 04/22/2014 11:05 PM, Richard Davies wrote:
> > > Dwight Engen wrote:
> > >> Richard Davies wrote:
> > >>> Vladimir Davydov wrote:
> > >>>> In short, kmem limiting for memory cgroups is currently broken.
> > >>>> Do not use it. We are working on making it usable though.
> > > ...
> > >>> What is the best mechanism available today, until kmem limits
> > >>> mature?
> > >>>
> > >>> RLIMIT_NPROC exists but is per-user, not per-container.
> > >>>
> > >>> Perhaps there is an up-to-date task counter patchset or similar?
> > >>
> > >> I updated Frederic's task counter patches and included Max
> > >> Kellermann's fork limiter here:
> > >>
> > >> http://thread.gmane.org/gmane.linux.kernel.containers/27212
> > >>
> > >> I can send you a more recent patchset (against 3.13.10) if you
> > >> would find it useful.
> > >
> > > Yes please, I would be interested in that. Ideally even against
> > > 3.14.1 if you have that too.
> > 
> > Dwight, do you have these patches in any public repo?
> > 
> > I would like to test them also.
> 
> Hi Marian, I put the patches against 3.13.11 and 3.14.1 up at:
> 
> git://github.com/dwengen/linux.git cpuacct-task-limit-3.13
> git://github.com/dwengen/linux.git cpuacct-task-limit-3.14

Thanks, Dwight.  FWIW I'm agreed with Tim, Dwight, Richard, and Marian
that a task limit would be a proper cgroup extension, and specifically
that approximating that with a kmem limit is not a reasonable substitute.

-serge

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