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:
> + 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;
>
