[PATCH] mm: memcg: remove obsolete memcg_has_children()

[Lukas Bulwahn <lukas.bulwahn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Commit 2ef1bf118c40 ("mm: memcg: deprecate the non-hierarchical mode")
removed the only use of memcg_has_children() in
mem_cgroup_hierarchy_write() as part of the feature deprecation.

Hence, since then, make CC=clang W=1 warns:

  mm/memcontrol.c:3421:20:
    warning: unused function 'memcg_has_children' [-Wunused-function]

Simply remove this obsolete unused function.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
applies cleanly on next-20201113, not on current master

Roman, please ack.

Andrew, please pick this minor non-urgent patch into your -next tree.

 mm/memcontrol.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f95ddb3e9898..d49d7c507284 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3415,19 +3415,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
 	return nr_reclaimed;
 }
 
-/*
- * Test whether @memcg has children, dead or alive.
- */
-static inline bool memcg_has_children(struct mem_cgroup *memcg)
-{
-	bool ret;
-
-	rcu_read_lock();
-	ret = css_next_child(NULL, &memcg->css);
-	rcu_read_unlock();
-	return ret;
-}
-
 /*
  * Reclaims as many pages from the given memcg as possible.
  *
-- 
2.17.1