Hello, On Thu, May 05, 2016 at 09:41:31AM +0800, Wanpeng Li wrote: > The boot CPU handles housekeeping duty(unbound timers, workqueues, > timekeeping, ...) on behalf of full dynticks CPUs. It must remain > online when nohz full is enabled. There is a priority set to every > notifier_blocks: > > workqueue_cpu_up > tick_nohz_cpu_down > workqueue_cpu_down > > So tick_nohz_cpu_down callback failed when down prepare cpu 0, and > notifier_blocks behind tick_nohz_cpu_down will not be called any > more, which leads to workers are actually not unbound. Then hotplug > state machine will fallback to undo and online cpu 0 again. Workers > will be rebound unconditionally even if they are not unbound and > trigger the warning in this progress.
I'm a bit confused. Are you saying that the hotplug statemachine may invoke CPU_DOWN_FAILED w/o preceding CPU_DOWN on the same callback? Thanks. -- tejun
