diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index cd6047c..09b7325 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -476,10 +476,12 @@
 
 /*
  * Because there is no preemptable RCU, there can be no readers blocked,
- * so there is no need to check for blocked tasks.
+ * so there is no need to check for blocked tasks.  So check only for
+ * bogus qsmask values.
  */
 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
 {
+	WARN_ON_ONCE(rnp->qsmask);
 }
 
 /*