--- a/mm/memcontrol.c~mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root +++ a/mm/memcontrol.c @@ -2254,7 +2254,8 @@ static void reclaim_high(struct mem_cgro continue; memcg_memory_event(memcg, MEMCG_HIGH); try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); - } while ((memcg = parent_mem_cgroup(memcg))); + } while ((memcg = parent_mem_cgroup(memcg)) && + !mem_cgroup_is_root(memcg)); } static void high_work_func(struct work_struct *work)