From: Chris Down <chris@xxxxxxxxxxxxxx> Subject: mm, memcg: bypass high reclaim iteration for cgroup hierarchy root The root of the hierarchy cannot have high set, so we will never reclaim based on it. This makes that clearer and avoids another entry. Link: http://lkml.kernel.org/r/20200312164137.GA1753625@xxxxxxxxxxxxxx Signed-off-by: Chris Down <chris@xxxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- 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) _
