diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
index 1591f6b..900badd 100644
--- a/kernel/locking/rwsem-spinlock.c
+++ b/kernel/locking/rwsem-spinlock.c
@@ -155,6 +155,7 @@ void __sched __down_read(struct rw_semaphore *sem)
 
 	/* wait to be given the lock */
 	for (;;) {
+		mb();
 		if (!waiter.task)
 			break;
 		schedule();