> diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
> index 16865475120b..2605dd234a13 100644
> --- a/kernel/rcu/tree_nocb.h
> +++ b/kernel/rcu/tree_nocb.h
> @@ -891,7 +891,18 @@ static void nocb_cb_wait(struct rcu_data *rdp)
> swait_event_interruptible_exclusive(rdp->nocb_cb_wq,
> nocb_cb_wait_cond(rdp));
> if (kthread_should_park()) {
> - kthread_parkme();
> + /*
> + * kthread_park() must be preceded by an rcu_barrier().
> + * But yet another rcu_barrier() might have sneaked in between
> + * the barrier callback execution and the callbacks counter
> + * decrement.
> + */
> + if (rdp->nocb_cb_sleep) {
Is READ_ONCE() not required here?
- Neeraj
> + rcu_nocb_lock_irqsave(rdp, flags);
> + WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist));
> + rcu_nocb_unlock_irqrestore(rdp, flags);
> + kthread_parkme();
> + }
> } else if (READ_ONCE(rdp->nocb_cb_sleep)) {
> WARN_ON(signal_pending(current));
> trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WokeEmpty"));
