revert "memcg: track all children over limit in the root"

Revert commit 1be171d60bdd ("memcg: track all children over limit in the
root")

I merged this prematurely - Michal and Johannes still disagree about the
overall design direction and the future remains unclear.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d5ff3ce13029b2c99b4ed402898ae0c76a143fde..5ee0af463f2ecad7d377ba60822f1e096f91601a 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -851,15 +851,9 @@ 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);
 }
 
@@ -6112,9 +6106,6 @@ 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);