1 files changed, 9 insertions, 0 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 848fc6c195d2..46717d6c62b7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -864,9 +864,15 @@ static void mem_cgroup_update_soft_limit(struct mem_cgroup *memcg)
         /*
          * Necessary to update all ancestors when hierarchy is used
          * because their event counter is not touched.
+         * We track children even outside the hierarchy for the root
+         * cgroup because tree walk starting at root should visit
+         * all cgroups and we want to prevent from pointless tree
+         * walk if no children is below the limit.
          */
         while (delta && (parent = parent_mem_cgroup(parent)))
                 atomic_add(delta, &parent->children_in_excess);
+        if (memcg != root_mem_cgroup && !root_mem_cgroup->use_hierarchy)
+                atomic_add(delta, &root_mem_cgroup->children_in_excess);
         spin_unlock(&memcg->soft_lock);
 }
 
@@ -6043,6 +6049,9 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
         if (memcg->soft_contributed) {
                 while ((memcg = parent_mem_cgroup(memcg)))
                         atomic_dec(&memcg->children_in_excess);
+
+                if (memcg != root_mem_cgroup && !root_mem_cgroup->use_hierarchy)
+                        atomic_dec(&root_mem_cgroup->children_in_excess);
         }
         mem_cgroup_destroy_all_caches(memcg);
         vmpressure_cleanup(&memcg->vmpressure);