Messages in this thread | | | Date | Thu, 6 Sep 2018 10:10:09 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] kernel: cpu: Handle hotplug failure for state CPUHP_AP_IDLE_DEAD |
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On Wed, 5 Sep 2018, Prakruthi Deepak Heragu wrote:
> Once the tear down hotplug handler is run, cpu is dead and enters > into CPUHP_AP_IDLE_DEAD state. Any callbacks that fail in the state > machine with state < CPUHP_AP_IDLE must be treated as fatal as this > could result into timer not beig migrated away from dead cpu and run > into issues like work queue lock ups, sched_clock timer wrapping to > zero as sched_clock_poll which is in the hrtimer base of cpu being > hotplugged does not get migrated.
BUG_ON() is the last resort when there is no other way out. And there is no reason to treat such a failure as fatal unconditionally.
Why would any of those callback fail at all? And if that ever happens, then we really can be smarter than just giving up.
Thanks,
tglx
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