Re: [RFC PATCH] mm: memcg/slab: Stop reparented obj_cgroups from charging root

[Johannes Weiner]

On Tue, Oct 20, 2020 at 10:07:17AM -0700, Roman Gushchin wrote:
> If we want these counter to function properly, then we should go into the opposite
> direction and remove the special handling of the root memory cgroup in many places.

I suspect this is also by far the most robust solution from a code and
maintenance POV.

I don't recall the page counter at the root level having been a
concern in recent years, even though it's widely used in production
environments. It's lockless and cache compact. It's also per-cpu
batched, which means it isn't actually part of the memcg hotpath.