diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index a8f553354405..f8141fa94f75 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2068,6 +2068,7 @@ static bool rcu_cpu_has_nonlazy_callbacks(int cpu)
  */
 static void rcu_idle_gp_timer_func(unsigned long unused)
 {
+	WARN_ON_ONCE(1); /* Getting here can hang the system... */
 	trace_rcu_prep_idle("Timer");
 }