On 1/30/21 11:20 AM, Jarkko Sakkinen wrote: ... > Example scenario would such that all removals "side-channel" through > the notifier callback. Then mmu_notifier_unregister() gets called > exactly zero times. No MMU notifier srcu sync would be then happening. > > NOTE: There's bunch of other examples, I'm just giving one. Could you flesh this out a bit? I don't quite understand the scenario from what you describe above. In any case, I'm open to other implementations that fix the race we know about. If you think you have a better fix, I'm happy to review it and make sure it closes the other race.