On Mon, May 25, 2020 at 05:07:22PM +0200, Vlastimil Babka wrote: > On 4/22/20 10:46 PM, Roman Gushchin wrote: > > Store the obj_cgroup pointer in the corresponding place of > > page->obj_cgroups for each allocated non-root slab object. > > Make sure that each allocated object holds a reference to obj_cgroup. > > > > Objcg pointer is obtained from the memcg->objcg dereferencing > > in memcg_kmem_get_cache() and passed from pre_alloc_hook to > > post_alloc_hook. Then in case of successful allocation(s) it's > > getting stored in the page->obj_cgroups vector. > > > > The objcg obtaining part look a bit bulky now, but it will be simplified > > by next commits in the series. > > > > Signed-off-by: Roman Gushchin <guro@xxxxxx> > > Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> > > Nit below: > > > diff --git a/mm/slab.h b/mm/slab.h > > index 44def57f050e..525e09e05743 100644 > > --- a/mm/slab.h > > +++ b/mm/slab.h > ... > > @@ -636,8 +684,8 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags, > > s->flags, flags); > > } > > > > - if (memcg_kmem_enabled()) > > - memcg_kmem_put_cache(s); > > + if (!is_root_cache(s)) > > + memcg_slab_post_alloc_hook(s, objcg, size, p); > > } > > > > #ifndef CONFIG_SLOB > > Keep also the memcg_kmem_enabled() static key check, like elsewhere? > Ok, will add, it can speed things up a little bit. My only concern is that the code is not ready for memcg_kmem_enabled() turning negative after being positive. But it's not a concern, right? Actually, we can simplify memcg_kmem_enabled() mechanics and enable it only once as soon as the first memcg is fully initialized. I don't think there is any value in tracking the actual number of active memcgs. Thanks!
