On Wed, Aug 25, 2021 at 12:54:15PM +0200, Nicolas Saenz Julienne wrote:

With the introduction of ee9707e8593d ("cgroup/cpuset: Enable memory
migration for cpuset v2") attaching a process to a different cgroup will
trigger a memory migration regardless of whether it's really needed.
Memory migration is an expensive operation, so bypass it if the
nodemasks passed to cpuset_migrate_mm() are equal.

Note that we're not only avoiding the migration work itself, but also a
call to lru_cache_disable(), which triggers and flushes an LRU drain
work on every online CPU.

Signed-off-by: Nicolas Saenz Julienne <redacted>

Applied to cgroup/for-5.15.

Thanks.

-- 
tejun