Re: [PATCH 3/4] sched: WARN when migrating to an offline CPU

[Levin, Alexander (Sasha Levin)]

On Thu, Sep 28, 2017 at 12:35:41PM +0200, Peter Zijlstra wrote:
>On Thu, Sep 28, 2017 at 02:14:15AM -0700, Sasha Levin wrote:
>> On Thu, Sep 7, 2017 at 8:03 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>> > Migrating tasks to offline CPUs is a pretty big fail, warn about it.
>>
>> Hey Peter,
>>
>> This seems to get hit on the latest -next:
>>
>> [2035565360.446794] Unregister pv shared memory for cpu 2
>> [2035565360.467930] numa_remove_cpu cpu 2 node 2: mask now 6
>> [2035565360.471431] ------------[ cut here ]------------
>> [2035565360.472548] WARNING: CPU: 2 PID: 24 at > kernel/sched/core.c:1178 set_task_cpu (kernel/sched/core.c:1157)
>> [2035565360.473840] Modules linked in:
>> [2035565360.474632] CPU: 2 PID: 24 Comm: migration/2 Not tainted > 4.14.0-rc2-next-20170927+ #252
>
>Urgh, weird. That really shouldn't happen. Can you easily reproduce?

Looks like yes. Seems like it's enough to stress CPU hotplug + trinity.

If you have patches you want me try send them my way.

-- 

Thanks,
Sasha