diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 156ac8d0418b..c88240a685ec 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3612,6 +3612,7 @@ void rcu_cpu_starting(unsigned int cpu)
 	nbits = bitmap_weight(&oldmask, BITS_PER_LONG);
 	/* Allow lockless access for expedited grace periods. */
 	smp_store_release(&rcu_state.ncpus, rcu_state.ncpus + nbits); /* ^^^ */
+	ASSERT_EXCLUSIVE_WRITER(rcu_state.ncpus);
 	rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */
 	rdp->rcu_onl_gp_seq = READ_ONCE(rcu_state.gp_seq);
 	rdp->rcu_onl_gp_flags = READ_ONCE(rcu_state.gp_flags);