Re: [Intel-gfx] [PATCH 29/29] mm: shrinker: move shrinker-related code into a separate file

[Sergey Senozhatsky]

On (23/06/22 16:53), Qi Zheng wrote:
> +/*
> + * Remove one
> + */
> +void unregister_shrinker(struct shrinker *shrinker)
> +{
> +     struct dentry *debugfs_entry;
> +     int debugfs_id;
> +
> +     if (!(shrinker->flags & SHRINKER_REGISTERED))
> +             return;
> +
> +     shrinker_put(shrinker);
> +     wait_for_completion(&shrinker->completion_wait);
> +
> +     mutex_lock(&shrinker_mutex);
> +     list_del_rcu(&shrinker->list);

Should this function wait for RCU grace period(s) before it goes
touching shrinker fields?

> +     shrinker->flags &= ~SHRINKER_REGISTERED;
> +     if (shrinker->flags & SHRINKER_MEMCG_AWARE)
> +             unregister_memcg_shrinker(shrinker);
> +     debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
> +     mutex_unlock(&shrinker_mutex);
> +
> +     shrinker_debugfs_remove(debugfs_entry, debugfs_id);
> +
> +     kfree(shrinker->nr_deferred);
> +     shrinker->nr_deferred = NULL;
> +}
> +EXPORT_SYMBOL(unregister_shrinker);

[..]

> +void shrinker_free(struct shrinker *shrinker)
> +{
> +     kfree(shrinker);
> +}
> +EXPORT_SYMBOL(shrinker_free);
> +
> +void unregister_and_free_shrinker(struct shrinker *shrinker)
> +{
> +     unregister_shrinker(shrinker);
> +     kfree_rcu(shrinker, rcu);
> +}

Seems like this

        unregister_shrinker();
        shrinker_free();

is not exact equivalent of this

        unregister_and_free_shrinker();