[PATCH] mm, memcg: clean up reclaim iter array

[Yafang Shao <laoar.shao@xxxxxxxxx>]

The mem_cgroup_reclaim_cookie is only used in memcg softlimit reclaim now,
and the priority of the reclaim is always 0. We don't need to define the
iter in struct mem_cgroup_per_node as an array any more. That could make
the code more clear and save some space.

Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
---
 include/linux/memcontrol.h |  3 +--
 mm/memcontrol.c            | 11 +++--------
 2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0c762e8..7d99a65 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -58,7 +58,6 @@ enum mem_cgroup_protection {
 
 struct mem_cgroup_reclaim_cookie {
 	pg_data_t *pgdat;
-	int priority;
 	unsigned int generation;
 };
 
@@ -126,7 +125,7 @@ struct mem_cgroup_per_node {
 
 	unsigned long		lru_zone_size[MAX_NR_ZONES][NR_LRU_LISTS];
 
-	struct mem_cgroup_reclaim_iter	iter[DEF_PRIORITY + 1];
+	struct mem_cgroup_reclaim_iter	iter;
 
 	struct memcg_shrinker_map __rcu	*shrinker_map;
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1c4c08b..5d9b00f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1052,7 +1052,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 		struct mem_cgroup_per_node *mz;
 
 		mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id);
-		iter = &mz->iter[reclaim->priority];
+		iter = &mz->iter;
 
 		if (prev && reclaim->generation != iter->generation)
 			goto out_unlock;
@@ -1152,15 +1152,11 @@ static void __invalidate_reclaim_iterators(struct mem_cgroup *from,
 	struct mem_cgroup_reclaim_iter *iter;
 	struct mem_cgroup_per_node *mz;
 	int nid;
-	int i;
 
 	for_each_node(nid) {
 		mz = mem_cgroup_nodeinfo(from, nid);
-		for (i = 0; i <= DEF_PRIORITY; i++) {
-			iter = &mz->iter[i];
-			cmpxchg(&iter->position,
-				dead_memcg, NULL);
-		}
+		iter = &mz->iter;
+		cmpxchg(&iter->position, dead_memcg, NULL);
 	}
 }
 
@@ -1705,7 +1701,6 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
 	unsigned long nr_scanned;
 	struct mem_cgroup_reclaim_cookie reclaim = {
 		.pgdat = pgdat,
-		.priority = 0,
 	};
 
 	excess = soft_limit_excess(root_memcg);
-- 
1.8.3.1