1 files changed, 40 insertions, 22 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8e0988fee888..a9318963d5d5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6093,7 +6093,7 @@ err_cleanup:
 static struct cgroup_subsys_state * __ref
 mem_cgroup_css_alloc(struct cgroup *cont)
 {
-        struct mem_cgroup *memcg, *parent;
+        struct mem_cgroup *memcg;
         long error = -ENOMEM;
         int node;
 
@@ -6108,7 +6108,7 @@ mem_cgroup_css_alloc(struct cgroup *cont)
         /* root ? */
         if (cont->parent == NULL) {
                 int cpu;
-                parent = NULL;
+
                 if (mem_cgroup_soft_limit_tree_init())
                         goto free_out;
                 root_mem_cgroup = memcg;
@@ -6117,13 +6117,43 @@ mem_cgroup_css_alloc(struct cgroup *cont)
                                                 &per_cpu(memcg_stock, cpu);
                         INIT_WORK(&stock->work, drain_local_stock);
                 }
-        } else {
-                parent = mem_cgroup_from_cont(cont->parent);
-                memcg->use_hierarchy = parent->use_hierarchy;
-                memcg->oom_kill_disable = parent->oom_kill_disable;
+
+                res_counter_init(&memcg->res, NULL);
+                res_counter_init(&memcg->memsw, NULL);
+                res_counter_init(&memcg->kmem, NULL);
         }
 
-        if (parent && parent->use_hierarchy) {
+        memcg->last_scanned_node = MAX_NUMNODES;
+        INIT_LIST_HEAD(&memcg->oom_notify);
+        atomic_set(&memcg->refcnt, 1);
+        memcg->move_charge_at_immigrate = 0;
+        mutex_init(&memcg->thresholds_lock);
+        spin_lock_init(&memcg->move_lock);
+
+        return &memcg->css;
+
+free_out:
+        __mem_cgroup_free(memcg);
+        return ERR_PTR(error);
+}
+
+static int
+mem_cgroup_css_online(struct cgroup *cont)
+{
+        struct mem_cgroup *memcg, *parent;
+        int error = 0;
+
+        if (!cont->parent)
+                return 0;
+
+        memcg = mem_cgroup_from_cont(cont);
+        parent = mem_cgroup_from_cont(cont->parent);
+
+        memcg->use_hierarchy = parent->use_hierarchy;
+        memcg->oom_kill_disable = parent->oom_kill_disable;
+        memcg->swappiness = mem_cgroup_swappiness(parent);
+
+        if (parent->use_hierarchy) {
                 res_counter_init(&memcg->res, &parent->res);
                 res_counter_init(&memcg->memsw, &parent->memsw);
                 res_counter_init(&memcg->kmem, &parent->kmem);
@@ -6144,18 +6174,9 @@ mem_cgroup_css_alloc(struct cgroup *cont)
                  * much sense so let cgroup subsystem know about this
                  * unfortunate state in our controller.
                  */
-                if (parent && parent != root_mem_cgroup)
+                if (parent != root_mem_cgroup)
                         mem_cgroup_subsys.broken_hierarchy = true;
         }
-        memcg->last_scanned_node = MAX_NUMNODES;
-        INIT_LIST_HEAD(&memcg->oom_notify);
-
-        if (parent)
-                memcg->swappiness = mem_cgroup_swappiness(parent);
-        atomic_set(&memcg->refcnt, 1);
-        memcg->move_charge_at_immigrate = 0;
-        mutex_init(&memcg->thresholds_lock);
-        spin_lock_init(&memcg->move_lock);
 
         error = memcg_init_kmem(memcg, &mem_cgroup_subsys);
         if (error) {
@@ -6165,12 +6186,8 @@ mem_cgroup_css_alloc(struct cgroup *cont)
                  * call __mem_cgroup_free, so return directly
                  */
                 mem_cgroup_put(memcg);
-                return ERR_PTR(error);
         }
-        return &memcg->css;
-free_out:
-        __mem_cgroup_free(memcg);
-        return ERR_PTR(error);
+        return error;
 }
 
 static void mem_cgroup_css_offline(struct cgroup *cont)
@@ -6780,6 +6797,7 @@ struct cgroup_subsys mem_cgroup_subsys = {
         .name = "memory",
         .subsys_id = mem_cgroup_subsys_id,
         .css_alloc = mem_cgroup_css_alloc,
+        .css_online = mem_cgroup_css_online,
         .css_offline = mem_cgroup_css_offline,
         .css_free = mem_cgroup_css_free,
         .can_attach = mem_cgroup_can_attach,