On Tue, Aug 13, 2019 at 02:31:17PM -0700, Andrew Morton wrote:

On Mon, 12 Aug 2019 16:37:54 -0700 Roman Gushchin guro@fb.com wrote:

...

Similar to vmstats, percpu caching of local vmevents leads to an accumulation of errors on non-leaf levels. This happens because some leftovers may remain in percpu caches, so that they are never propagated up by the cgroup tree and just disappear into nonexistence with on releasing of the memory cgroup.

To fix this issue let's accumulate and propagate percpu vmevents values before releasing the memory cgroup similar to what we're doing with vmstats.

Since on cpu hotplug we do flush percpu vmstats anyway, we can iterate only over online cpus.

Fixes: 42a300353577 ("mm: memcontrol: fix recursive statistics correctness & scalabilty")

No cc:stable?

Here too, cc:stable is definitely missing. Adding now. Thanks!