Re: [v9 4/5] mm, oom: add cgroup v2 mount option for cgroup-aware OOM killer

[Roman Gushchin]

On Tue, Oct 03, 2017 at 01:50:36PM +0200, Michal Hocko wrote:
> On Wed 27-09-17 14:09:35, Roman Gushchin wrote:
> > Add a "groupoom" cgroup v2 mount option to enable the cgroup-aware
> > OOM killer. If not set, the OOM selection is performed in
> > a "traditional" per-process way.
> > 
> > The behavior can be changed dynamically by remounting the cgroupfs.
> 
> I do not have a strong preference about this. I would just be worried
> that it is usually systemd which tries to own the whole hierarchy

I actually like this fact.

It gives us the opportunity to change the default behavior for most users
at the point when we'll be sure that new behavior is better; but at the same
time we'll save full compatibility on the kernel level.
With growing popularity of memory cgroups, I don't think that hiding
this functionality with a boot option makes any sense. It's just not
this type of feature, that should be hidden.