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-rw-r--r--mm/memcontrol.c9
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);