Re: [PATCH 3/9] slab: simplify shutdown_memcg_caches()

Tejun Heo
2017-01-14T15:53:43Z

On Sat, Jan 14, 2017 at 10:38:01AM -0500, Tejun Heo wrote:
> On Sat, Jan 14, 2017 at 04:27:22PM +0300, Vladimir Davydov wrote:
> > > - * Second, shutdown all caches left from memory cgroups that are now
> > > - * offline.
> > > + * Shutdown all caches.
> > > */
> > > list_for_each_entry_safe(c, c2, &s->memcg_params.list,
> > > memcg_params.list)
> > > shutdown_cache(c);
> >
> > The point of this complexity was to leave caches that happen to have
> > objects when kmem_cache_destroy() is called on the list, so that they
> > could be reused later. This behavior was inherited from the global
>
> Ah, right, I misread the branch. I don't quite get how the cache can
> be reused later tho? This is called when the memcg gets released and
> a clear error condition - the caller, kmem_cache_destroy(), handles it
> as an error condition too.

I think I understand it now. This is the alias being able to find and
reuse the cache. Heh, that's a weird optimization for a corner error
case. Anyways, I'll drop this patch.

Thanks.

--
tejun