Messages in this thread | | | Date | Mon, 3 Feb 2020 18:37:32 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH RT 1/2] sched: migrate_enable: Use per-cpu cpu_stop_work |
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On 2020-01-24 06:11:46 [-0500], Scott Wood wrote: > Commit e6c287b1512d ("sched: migrate_enable: Use stop_one_cpu_nowait()") > adds a busy wait to deal with an edge case where the migrated thread > can resume running on another CPU before the stopper has consumed > cpu_stop_work. However, this is done with preemption disabled and can > potentially lead to deadlock. > > While it is not guaranteed that the cpu_stop_work will be consumed before > the migrating thread resumes and exits the stack frame, it is guaranteed > that nothing other than the stopper can run on the old cpu between the > migrating thread scheduling out and the cpu_stop_work being consumed. > Thus, we can store cpu_stop_work in per-cpu data without it being > reused too early. > > Fixes: e6c287b1512d ("sched: migrate_enable: Use stop_one_cpu_nowait()") > Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Signed-off-by: Scott Wood <swood@redhat.com>
Yes, perfect, thank you.
Sebastian
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