mm: vmpressure: use mem_cgroup_is_root API

Use mem_cgroup_is_root() API to check if memcg is root memcg instead of
open coding.

Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/1581398649-125989-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmpressure.c b/mm/vmpressure.c
index 0590f00..d69019f 100644 (file)
--- a/mm/vmpressure.c
+++ b/mm/vmpressure.c
@@ -280,7 +280,7 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
                enum vmpressure_levels level;
 
                /* For now, no users for root-level efficiency */
-               if (!memcg || memcg == root_mem_cgroup)
+               if (!memcg || mem_cgroup_is_root(memcg))
                        return;
 
                spin_lock(&vmpr->sr_lock);