mm/sl[aou]b: Move list_add() to slab_common.c

Move the code to append the new kmem_cache to the list of slab caches to
the kmem_cache_create code in the shared code.

This is possible now since the acquisition of the mutex was moved into
kmem_cache_create().

Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

mm/slob.c

@@ -540,6 +540,10 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 
 void kmem_cache_destroy(struct kmem_cache *c)
 {
+	mutex_lock(&slab_mutex);
+	list_del(&c->list);
+	mutex_unlock(&slab_mutex);
+
 	kmemleak_free(c);
 	if (c->flags & SLAB_DESTROY_BY_RCU)
 		rcu_barrier();