A technique for determining when it is safe to use scheduler lock-acquiring wakeups to defer quiescent states in real-time preemptible read-copy update (RCU). A determination may be made whether a deferred quiescent-state reporting request that defers the reporting of an RCU quiescent state on behalf of a target computer task is warranted. If so, it may be determined whether a previous deferred quiescent-state reporting request on behalf of the target computer task remains pending. A request may be issued for deferred quiescent-state report processing that reports a deferred quiescent state. The request for deferred quiescent-state report processing may be issued in a manner selected according to a result of the determining whether a previous deferred quiescent-state reporting request remains pending.