diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index a2fb14b..000719c 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2767,8 +2767,11 @@
 	smp_wmb();
 	cic->key = cfqd_dead_key(cfqd);
 
-	if (ioc->ioc_data == cic)
+	if (rcu_dereference(ioc->ioc_data) == cic) {
+		spin_lock(&ioc->lock);
 		rcu_assign_pointer(ioc->ioc_data, NULL);
+		spin_unlock(&ioc->lock);
+	}
 
 	if (cic->cfqq[BLK_RW_ASYNC]) {
 		cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);