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.
