Re: [PATCH v6 6/9] mm: multigenerational lru: aging

[Michal Hocko]

On Tue 04-01-22 13:22:25, Yu Zhao wrote:
[...]
> +static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
> +{
> +	struct mem_cgroup *memcg;
> +	bool success = false;
> +	unsigned long min_ttl = READ_ONCE(lru_gen_min_ttl);
> +
> +	VM_BUG_ON(!current_is_kswapd());
> +
> +	current->reclaim_state->mm_walk = &pgdat->mm_walk;
> +
> +	memcg = mem_cgroup_iter(NULL, NULL, NULL);
> +	do {
> +		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
> +
> +		if (age_lruvec(lruvec, sc, min_ttl))
> +			success = true;
> +
> +		cond_resched();
> +	} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)));
> +
> +	if (!success && mutex_trylock(&oom_lock)) {
> +		struct oom_control oc = {
> +			.gfp_mask = sc->gfp_mask,
> +			.order = sc->order,
> +		};
> +
> +		if (!oom_reaping_in_progress())
> +			out_of_memory(&oc);
> +
> +		mutex_unlock(&oom_lock);
> +	}

Why do you need to trigger oom killer from this path? Why cannot you
rely on the page allocator to do that like we do now?
-- 
Michal Hocko
SUSE Labs