On Fri, Jan 29, 2021 at 7:40 AM Vlastimil Babka <vbabka@xxxxxxx> wrote:
>
> On 1/28/21 12:33 AM, Yang Shi wrote:
> > Now nr_deferred is available on per memcg level for memcg aware shrinkers, so don't need
> > allocate shrinker->nr_deferred for such shrinkers anymore.
> >
> > The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or memcg is disabled
> > by kernel command line, then shrinker's SHRINKER_MEMCG_AWARE flag would be cleared.
> > This makes the implementation of this patch simpler.
> >
> > Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> > @@ -525,8 +528,20 @@ unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone
> > */
> > int prealloc_shrinker(struct shrinker *shrinker)
> > {
> > - unsigned int size = sizeof(*shrinker->nr_deferred);
> > + unsigned int size;
> > + int err;
> > +
> > + if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
> > + err = prealloc_memcg_shrinker(shrinker);
> > + if (!err)
> > + return 0;
>
> Nit: this err == 0 case is covered below:
Aha, thanks. Will fix in v6.
>
> > + if (err != -ENOSYS)
> > + return err;
> > +
> > + shrinker->flags &= ~SHRINKER_MEMCG_AWARE;
> > + }
> >
> > + size = sizeof(*shrinker->nr_deferred);
> > if (shrinker->flags & SHRINKER_NUMA_AWARE)
> > size *= nr_node_ids;
> >
