Re: [PATCH] mm: memcg/slab: wait for !root kmem_cache refcnt killing on root kmem_cache destruction

Michal Hocko
2019-11-27T12:32:31Z

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?
--
Michal Hocko
SUSE Labs