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>> + >> + if (rtime > RSEQ_UNPREEMPTED_THRESHOLD) >> + rseq_preempt(t); >> +} > > This confused me. > > The goal seems to be to tickle __rseq_handle_notify_resume() so it'll > end up queueing that work thing. But why do we want to set PREEMPT_BIT > here? In that scenario, we trigger (from tick) the fact that we may recompact the mm_cid, and thus need to update the rseq mm_cid field before returning to userspace. Changing the value of the mm_cid field while userspace is within a rseq critical section should abort the critical section, because the rseq critical section should be able to expect the mm_cid to be invariant for the whole c.s.. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com