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Commit 30361e51 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
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revert "memcg: track children in soft limit excess to improve soft limit" 



Revert commit 7d910c05 ("memcg: track children in soft limit excess
to improve soft limit")

I merged this prematurely - Michal and Johannes still disagree about the
overall design direction and the future remains unclear.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3120055e

mm/memcontrol.c

+0 −71
Original line number Diff line number Diff line
@@ -124,7 +124,6 @@ static const char * const mem_cgroup_lru_names[] = { 
 */

enum mem_cgroup_events_target {

	MEM_CGROUP_TARGET_THRESH,

	MEM_CGROUP_TARGET_SOFTLIMIT,

	MEM_CGROUP_TARGET_NUMAINFO,

	MEM_CGROUP_NTARGETS,

};
@@ -303,22 +302,6 @@ struct mem_cgroup { 
	atomic_t	numainfo_events;

	atomic_t	numainfo_updating;

#endif

	/*

	 * Protects soft_contributed transitions.

	 * See mem_cgroup_update_soft_limit

	 */

	spinlock_t soft_lock;



	/*

	 * If true then this group has increased parents' children_in_excess

	 * when it got over the soft limit.

	 * When a group falls bellow the soft limit, parents' children_in_excess

	 * is decreased and soft_contributed changed to false.

	 */

	bool soft_contributed;



	/* Number of children that are in soft limit excess */

	atomic_t children_in_excess;



	struct mem_cgroup_per_node *nodeinfo[0];

	/* WARNING: nodeinfo must be the last member here */
@@ -806,9 +789,6 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, 
		case MEM_CGROUP_TARGET_THRESH:

			next = val + THRESHOLDS_EVENTS_TARGET;

			break;

		case MEM_CGROUP_TARGET_SOFTLIMIT:

			next = val + SOFTLIMIT_EVENTS_TARGET;

			break;

		case MEM_CGROUP_TARGET_NUMAINFO:

			next = val + NUMAINFO_EVENTS_TARGET;

			break;
@@ -821,42 +801,6 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, 
	return false;

}



/*

 * Called from rate-limited memcg_check_events when enough

 * MEM_CGROUP_TARGET_SOFTLIMIT events are accumulated and it makes sure

 * that all the parents up the hierarchy will be notified that this group

 * is in excess or that it is not in excess anymore. mmecg->soft_contributed

 * makes the transition a single action whenever the state flips from one to

 * the other.

 */

static void mem_cgroup_update_soft_limit(struct mem_cgroup *memcg)

{

	unsigned long long excess = res_counter_soft_limit_excess(&memcg->res);

	struct mem_cgroup *parent = memcg;

	int delta = 0;



	spin_lock(&memcg->soft_lock);

	if (excess) {

		if (!memcg->soft_contributed) {

			delta = 1;

			memcg->soft_contributed = true;

		}

	} else {

		if (memcg->soft_contributed) {

			delta = -1;

			memcg->soft_contributed = false;

		}

	}



	/*

	 * Necessary to update all ancestors when hierarchy is used

	 * because their event counter is not touched.

	 */

	while (delta && (parent = parent_mem_cgroup(parent)))

		atomic_add(delta, &parent->children_in_excess);

	spin_unlock(&memcg->soft_lock);

}



/*

 * Check events in order.

 *
@@ -867,11 +811,8 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) 
	/* threshold event is triggered in finer grain than soft limit */

	if (unlikely(mem_cgroup_event_ratelimit(memcg,

						MEM_CGROUP_TARGET_THRESH))) {

		bool do_softlimit;

		bool do_numainfo __maybe_unused;



		do_softlimit = mem_cgroup_event_ratelimit(memcg,

						MEM_CGROUP_TARGET_SOFTLIMIT);

#if MAX_NUMNODES > 1

		do_numainfo = mem_cgroup_event_ratelimit(memcg,

						MEM_CGROUP_TARGET_NUMAINFO);
@@ -879,8 +820,6 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) 
		preempt_enable();



		mem_cgroup_threshold(memcg);

		if (unlikely(do_softlimit))

			mem_cgroup_update_soft_limit(memcg);

#if MAX_NUMNODES > 1

		if (unlikely(do_numainfo))

			atomic_inc(&memcg->numainfo_events);
@@ -1864,9 +1803,6 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg) 
 * hierarchy if

 *	a) it is over its soft limit

 *	b) any parent up the hierarchy is over its soft limit

 *

 * If the given group doesn't have any children over the limit then it

 * doesn't make any sense to iterate its subtree.

 */

enum mem_cgroup_filter_t

mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
@@ -1888,8 +1824,6 @@ mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg, 
			break;

	}



	if (!atomic_read(&memcg->children_in_excess))

		return SKIP_TREE;

	return SKIP;

}
@@ -6021,7 +5955,6 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 
	mutex_init(&memcg->thresholds_lock);

	spin_lock_init(&memcg->move_lock);

	vmpressure_init(&memcg->vmpressure);

	spin_lock_init(&memcg->soft_lock);



	return &memcg->css;
@@ -6099,10 +6032,6 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) 


	mem_cgroup_invalidate_reclaim_iterators(memcg);

	mem_cgroup_reparent_charges(memcg);

	if (memcg->soft_contributed) {

		while ((memcg = parent_mem_cgroup(memcg)))

			atomic_dec(&memcg->children_in_excess);

	}

	mem_cgroup_destroy_all_caches(memcg);

	vmpressure_cleanup(&memcg->vmpressure);

}