Don't you need 65k threads all contending on the same state for that to happen? Even if your process does have 65k threads, you'd need a pretty large critical s

Don't you need 65k threads all contending on the same state for that to happen? Even if your process does have 65k threads, you'd need a pretty large critical section for all of them to be preempted in an unlucky point. That said, it's better to rely on RCU/hazptr to solve ABA issues, but the extra bits are still useful to store state that can be CAS'd together with the pointer.