On Wed, Apr 11, 2018 at 09:07:30PM +0200, Sebastian Andrzej Siewior wrote:
>
> This already happens:
> - vmstat_shepherd() does get_online_cpus() and within this block it does
> queue_delayed_work_on(). So this has to wait until cpuhotplug
> completed before it can schedule something and then it won't schedule
> anything on the "off" CPU.
But can't we have something like this happen: ?
CPU0 CPU1 CPU2
---- ---- ----
get_online_cpus()
queue_work(vmstat_update, cpu1)
wakeup(kworker/1)
High prio task running
put_online_cpus()
Shutdown CPU 1
migrate kworker/1
schedule kworker/1
(smp_processor_id() != 1)
-- Steve
