mm: list_lru: only add memcg-aware lrus to the global lru list

The non-memcg-aware lru is always skiped when traversing the global lru
list, which is not efficient.  We can only add the memcg-aware lru to
the global lru list instead to make traversing more efficient.

Link: https://lkml.kernel.org/r/20211025124353.55781-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/list_lru.c

@@ -15,18 +15,29 @@
 #include "slab.h"
 
 #ifdef CONFIG_MEMCG_KMEM
-static LIST_HEAD(list_lrus);
+static LIST_HEAD(memcg_list_lrus);
 static DEFINE_MUTEX(list_lrus_mutex);
 
+static inline bool list_lru_memcg_aware(struct list_lru *lru)
+{
+	return lru->memcg_aware;
+}
+
 static void list_lru_register(struct list_lru *lru)
 {
+	if (!list_lru_memcg_aware(lru))
+		return;
+
 	mutex_lock(&list_lrus_mutex);
-	list_add(&lru->list, &list_lrus);
+	list_add(&lru->list, &memcg_list_lrus);
 	mutex_unlock(&list_lrus_mutex);
 }
 
 static void list_lru_unregister(struct list_lru *lru)
 {
+	if (!list_lru_memcg_aware(lru))
+		return;
+
 	mutex_lock(&list_lrus_mutex);
 	list_del(&lru->list);
 	mutex_unlock(&list_lrus_mutex);
@@ -37,11 +48,6 @@ static int lru_shrinker_id(struct list_lru *lru)
 	return lru->shrinker_id;
 }
 
-static inline bool list_lru_memcg_aware(struct list_lru *lru)
-{
-	return lru->memcg_aware;
-}
-
 static inline struct list_lru_one *
 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
 {
@@ -457,9 +463,6 @@ static int memcg_update_list_lru(struct list_lru *lru,
 {
 	int i;
 
-	if (!list_lru_memcg_aware(lru))
-		return 0;
-
 	for_each_node(i) {
 		if (memcg_update_list_lru_node(&lru->node[i],
 					       old_size, new_size))
@@ -482,9 +485,6 @@ static void memcg_cancel_update_list_lru(struct list_lru *lru,
 {
 	int i;
 
-	if (!list_lru_memcg_aware(lru))
-		return;
-
 	for_each_node(i)
 		memcg_cancel_update_list_lru_node(&lru->node[i],
 						  old_size, new_size);
@@ -497,7 +497,7 @@ int memcg_update_all_list_lrus(int new_size)
 	int old_size = memcg_nr_cache_ids;
 
 	mutex_lock(&list_lrus_mutex);
-	list_for_each_entry(lru, &list_lrus, list) {
+	list_for_each_entry(lru, &memcg_list_lrus, list) {
 		ret = memcg_update_list_lru(lru, old_size, new_size);
 		if (ret)
 			goto fail;
@@ -506,7 +506,7 @@ int memcg_update_all_list_lrus(int new_size)
 	mutex_unlock(&list_lrus_mutex);
 	return ret;
 fail:
-	list_for_each_entry_continue_reverse(lru, &list_lrus, list)
+	list_for_each_entry_continue_reverse(lru, &memcg_list_lrus, list)
 		memcg_cancel_update_list_lru(lru, old_size, new_size);
 	goto out;
 }
@@ -543,9 +543,6 @@ static void memcg_drain_list_lru(struct list_lru *lru,
 {
 	int i;
 
-	if (!list_lru_memcg_aware(lru))
-		return;
-
 	for_each_node(i)
 		memcg_drain_list_lru_node(lru, i, src_idx, dst_memcg);
 }
@@ -555,7 +552,7 @@ void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg)
 	struct list_lru *lru;
 
 	mutex_lock(&list_lrus_mutex);
-	list_for_each_entry(lru, &list_lrus, list)
+	list_for_each_entry(lru, &memcg_list_lrus, list)
 		memcg_drain_list_lru(lru, src_idx, dst_memcg);
 	mutex_unlock(&list_lrus_mutex);
 }