list_lru: get rid of ->active_nodes

The active_nodes mask allows us to skip empty nodes when walking over
list_lru items from all nodes in list_lru_count/walk.  However, these
functions are never called from hot paths, so it doesn't seem we need
such kind of optimization there.  OTOH, removing the mask will make it
easier to make list_lru per-memcg.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 10 deletions

diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index f500a2e39b13..53c1d6b78270 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -31,7 +31,6 @@ struct list_lru_node {
 
 struct list_lru {
         struct list_lru_node    *node;
-        nodemask_t              active_nodes;
 };
 
 void list_lru_destroy(struct list_lru *lru);
@@ -94,7 +93,7 @@ static inline unsigned long list_lru_count(struct list_lru *lru)
         long count = 0;
         int nid;
 
-        for_each_node_mask(nid, lru->active_nodes)
+        for_each_node_state(nid, N_NORMAL_MEMORY)
                 count += list_lru_count_node(lru, nid);
 
         return count;
@@ -142,7 +141,7 @@ list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
         long isolated = 0;
         int nid;
 
-        for_each_node_mask(nid, lru->active_nodes) {
+        for_each_node_state(nid, N_NORMAL_MEMORY) {
                 isolated += list_lru_walk_node(lru, nid, isolate,
                                                cb_arg, &nr_to_walk);
                 if (nr_to_walk <= 0)
diff --git a/mm/list_lru.c b/mm/list_lru.c
index f1a0db194173..07e198c77888 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -19,8 +19,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item)
         WARN_ON_ONCE(nlru->nr_items < 0);
         if (list_empty(item)) {
                 list_add_tail(item, &nlru->list);
-                if (nlru->nr_items++ == 0)
-                        node_set(nid, lru->active_nodes);
+                nlru->nr_items++;
                 spin_unlock(&nlru->lock);
                 return true;
         }
@@ -37,8 +36,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item)
         spin_lock(&nlru->lock);
         if (!list_empty(item)) {
                 list_del_init(item);
-                if (--nlru->nr_items == 0)
-                        node_clear(nid, lru->active_nodes);
+                nlru->nr_items--;
                 WARN_ON_ONCE(nlru->nr_items < 0);
                 spin_unlock(&nlru->lock);
                 return true;
@@ -90,8 +88,7 @@ restart:
                 case LRU_REMOVED_RETRY:
                         assert_spin_locked(&nlru->lock);
                 case LRU_REMOVED:
-                        if (--nlru->nr_items == 0)
-                                node_clear(nid, lru->active_nodes);
+                        nlru->nr_items--;
                         WARN_ON_ONCE(nlru->nr_items < 0);
                         isolated++;
                         /*
@@ -133,7 +130,6 @@ int list_lru_init_key(struct list_lru *lru, struct lock_class_key *key)
         if (!lru->node)
                 return -ENOMEM;
 
-        nodes_clear(lru->active_nodes);
         for (i = 0; i < nr_node_ids; i++) {
                 spin_lock_init(&lru->node[i].lock);
                 if (key)