[PATCH v2 06/21] mm: list_lru: only add the memcg aware lrus to the list_lrus

[Muchun Song]

We need to traverse every lru in the list_lrus in some routines, but skip
memcg non-aware lrus. However, we can only add the memcg aware lrus to
the list_lrus. This can be efficient to traverse the list.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 mm/list_lru.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/mm/list_lru.c b/mm/list_lru.c
index e86d4d055d3c..bed699edabe5 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -18,8 +18,16 @@
 static LIST_HEAD(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);
 	mutex_unlock(&list_lrus_mutex);
@@ -27,6 +35,9 @@ static void list_lru_register(struct list_lru *lru)
 
 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)
 {
@@ -460,9 +466,6 @@ 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))
@@ -485,9 +488,6 @@ 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);
@@ -546,9 +546,6 @@ 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);
 }
-- 
2.11.0