slub: do not put a slab to cpu partial list when cpu_partial is 0

In free path, we don't check number of cpu_partial, so one slab can
be linked in cpu partial list even if cpu_partial is 0. To prevent this,
we should check number of cpu_partial in put_cpu_partial().

Acked-by: Christoph Lameeter <cl@linux.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

mm/slub.c

@@ -1954,6 +1954,9 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
 	int pages;
 	int pobjects;
 
+	if (!s->cpu_partial)
+		return;
+
 	do {
 		pages = 0;
 		pobjects = 0;