On Wed, Nov 27, 2019 at 01:32:25PM +0100, Michal Hocko wrote:
On Tue 26-11-19 18:41:41, Roman Gushchin wrote:
On Tue, Nov 26, 2019 at 10:29:18AM +0100, Michal Hocko wrote:
On Mon 25-11-19 10:54:53, Roman Gushchin wrote:
[...]
So in a rare case when not all children kmem_caches are destroyed at the moment when the root kmem_cache is about to be gone, we need to wait another rcu grace period before destroying the root kmem_cache.
Could you explain how rare this really is please?
It seems that we don't destroy root kmem_caches with enabled memcg accounting that often, but maybe I'm biased here.
So this happens each time a root kmem_cache is destroyed? Which would imply that only dynamically created ones?
Yes, only dynamically created and only in those cases when destruction of the root cache happens immediately after the deactivation of the non-root cache. Tbh I can't imagine any other case except rmmod after removing the cgroup.
Thanks!