mm/slab: use list_move instead of list_del/list_add

Using list_move() instead of list_del() + list_add() to avoid needlessly
poisoning the next and prev values.

Link: http://lkml.kernel.org/r/1468929772-9174-1-git-send-email-weiyj_lk@163.com
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
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/slab.c

@@ -3452,8 +3452,7 @@ static void free_block(struct kmem_cache *cachep, void **objpp,
 		n->free_objects -= cachep->num;
 
 		page = list_last_entry(&n->slabs_free, struct page, lru);
-		list_del(&page->lru);
-		list_add(&page->lru, list);
+		list_move(&page->lru, list);
 	}
 }