mm/list_lru.c: move locking from __list_lru_walk_one() to its caller

Move the locking inside __list_lru_walk_one() to its caller.  This is a
preparation step in order to introduce list_lru_walk_one_irq() which
does spin_lock_irq() instead of spin_lock() for the locking.

Link: http://lkml.kernel.org/r/20180716111921.5365-3-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/list_lru.c b/mm/list_lru.c
index 522b98c..286f92a 100644 (file)
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -219,7 +219,6 @@ __list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
        struct list_head *item, *n;
        unsigned long isolated = 0;
 
-       spin_lock(&nlru->lock);
        l = list_lru_from_memcg_idx(nlru, memcg_idx);
 restart:
        list_for_each_safe(item, n, &l->list) {
@@ -265,8 +264,6 @@ restart:
                        BUG();
                }
        }
-
-       spin_unlock(&nlru->lock);
        return isolated;
 }
 
@@ -275,8 +272,14 @@ list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
                  list_lru_walk_cb isolate, void *cb_arg,
                  unsigned long *nr_to_walk)
 {
-       return __list_lru_walk_one(lru, nid, memcg_cache_id(memcg),
-                                  isolate, cb_arg, nr_to_walk);
+       struct list_lru_node *nlru = &lru->node[nid];
+       unsigned long ret;
+
+       spin_lock(&nlru->lock);
+       ret = __list_lru_walk_one(lru, nid, memcg_cache_id(memcg),
+                                 isolate, cb_arg, nr_to_walk);
+       spin_unlock(&nlru->lock);
+       return ret;
 }
 EXPORT_SYMBOL_GPL(list_lru_walk_one);
 
@@ -291,8 +294,13 @@ unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
                                      nr_to_walk);
        if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
                for_each_memcg_cache_index(memcg_idx) {
+                       struct list_lru_node *nlru = &lru->node[nid];
+
+                       spin_lock(&nlru->lock);
                        isolated += __list_lru_walk_one(lru, nid, memcg_idx,
                                                isolate, cb_arg, nr_to_walk);
+                       spin_unlock(&nlru->lock);
+
                        if (*nr_to_walk <= 0)
                                break;
                }