memcg: clean up memcg->nodeinfo

Remove struct mem_cgroup_lru_info and fold its single member, the variably
sized nodeinfo[0], directly into struct mem_cgroup.  This should make it
more obvious why it has to be the last member there.

Also move the comment that's above that special last member below it, so
it is more visible to somebody that considers appending to the struct
mem_cgroup.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2e851f453814529d0a3e032e9e5e1dd009a4b34a..2b7cd24d4cdaf815b28628204767026fef6a4fe8 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -187,10 +187,6 @@ struct mem_cgroup_per_node {
        struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
 };
 
-struct mem_cgroup_lru_info {
-       struct mem_cgroup_per_node *nodeinfo[0];
-};
-
 /*
  * Cgroups above their limits are maintained in a RB-Tree, independent of
  * their hierarchy representation
@@ -366,14 +362,8 @@ struct mem_cgroup {
        atomic_t        numainfo_updating;
 #endif
 
-       /*
-        * Per cgroup active and inactive list, similar to the
-        * per zone LRU lists.
-        *
-        * WARNING: This has to be the last element of the struct. Don't
-        * add new fields after this point.
-        */
-       struct mem_cgroup_lru_info info;
+       struct mem_cgroup_per_node *nodeinfo[0];
+       /* WARNING: nodeinfo must be the last member here */
 };
 
 static size_t memcg_size(void)
@@ -683,7 +673,7 @@ static struct mem_cgroup_per_zone *
 mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
 {
        VM_BUG_ON((unsigned)nid >= nr_node_ids);
-       return &memcg->info.nodeinfo[nid]->zoneinfo[zid];
+       return &memcg->nodeinfo[nid]->zoneinfo[zid];
 }
 
 struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
@@ -6087,13 +6077,13 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
                mz->on_tree = false;
                mz->memcg = memcg;
        }
-       memcg->info.nodeinfo[node] = pn;
+       memcg->nodeinfo[node] = pn;
        return 0;
 }
 
 static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
 {
-       kfree(memcg->info.nodeinfo[node]);
+       kfree(memcg->nodeinfo[node]);
 }
 
 static struct mem_cgroup *mem_cgroup_alloc(void)