On Tuesday, November 21, 2017 2:34:03 PM CET Peter Zijlstra wrote:
> On Tue, Nov 21, 2017 at 08:04:20PM +0800, Fengguang Wu wrote:
> > Hello,
> > 
> > FYI this happens in mainline kernel 4.14.0-00902-g43ff2f4.
> > It happens since 4.13.
> > 
> > It occurs in 7 out of 36 boots.
> > 
> > [   58.171538] no ifx modem active;
> > [   58.211860] ACPI: Preparing to enter system sleep state S5
> > [   58.216823] reboot: Power down
> > [   58.244526] acpi_power_off called
> > [   61.460467] ------------[ cut here ]------------
> > [   61.465481] WARNING: CPU: 0 PID: 11 at kernel/sched/core.c:1187 set_task_cpu+0x257/0x6b6:
> > 						set_task_cpu at kernel/sched/core.c:1187
> 
> Never seen that before.. but I can't even figure out how CPUs end up
> offline in that reboot path :/
> 
> So far I just get lost in the callback maze... Rafael any clues?
> 

Nope.

We used to offline nonboot CPUs in the reboot path, but we don't seem to
be doing that any more.