slub: remove kmemcg id from create_unique_id

This function is never called for memcg caches, because they are
unmergeable, so remove the dead code.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slub.c

@@ -5128,12 +5128,6 @@ static char *create_unique_id(struct kmem_cache *s)
 		*p++ = '-';
 	p += sprintf(p, "%07d", s->size);
 
-#ifdef CONFIG_MEMCG_KMEM
-	if (!is_root_cache(s))
-		p += sprintf(p, "-%08d",
-				memcg_cache_id(s->memcg_params->memcg));
-#endif
-
 	BUG_ON(p > name + ID_STR_LENGTH - 1);
 	return name;
 }