From: Shakeel Butt <shakeelb@xxxxxxxxxx> Subject: memcg: cleanup root memcg checks Replace the implicit checking of root memcg with explicit root memcg checking i.e. !css->parent with mem_cgroup_is_root(). Link: https://lkml.kernel.org/r/20210223205625.2792891-1-shakeelb@xxxxxxxxxx Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/memcontrol.c~memcg-cleanup-root-memcg-checks +++ a/mm/memcontrol.c @@ -4123,7 +4123,7 @@ static int mem_cgroup_swappiness_write(s if (val > 100) return -EINVAL; - if (css->parent) + if (!mem_cgroup_is_root(memcg)) memcg->swappiness = val; else vm_swappiness = val; @@ -4473,7 +4473,7 @@ static int mem_cgroup_oom_control_write( struct mem_cgroup *memcg = mem_cgroup_from_css(css); /* cannot set to root cgroup and only 0 and 1 are allowed */ - if (!css->parent || !((val == 0) || (val == 1))) + if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1))) return -EINVAL; memcg->oom_kill_disable = val; _
