lkml.org 
[lkml]   [2021]   [Jul]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: sched: Unexpected reschedule of offline CPU#2!
From
Date
[Henning, don't top-post ;)]

On 27.07.21 10:00, Henning Schild via Xenomai wrote:
> Was this ever resolved and if so can someone please point me to the
> patches? I started digging a bit but could not yet find how that
> continued.
>
> I am seeing similar or maybe the same problem on 4.19.192 with the
> ipipe patch from the xenomai project applied.
>

Before blaming the usual suspects, I have a general ordering question on
mainline below.

> regards,
> Henning
>
> Am Sat, 17 Aug 2019 22:21:48 +0200
> schrieb Thomas Gleixner <tglx@linutronix.de>:
>
>> On Fri, 16 Aug 2019, Guenter Roeck wrote:
>>> On Fri, Aug 16, 2019 at 12:22:22PM +0200, Thomas Gleixner wrote:
>>>> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
>>>> index 75fea0d48c0e..625627b1457c 100644
>>>> --- a/arch/x86/kernel/process.c
>>>> +++ b/arch/x86/kernel/process.c
>>>> @@ -601,6 +601,7 @@ void stop_this_cpu(void *dummy)
>>>> /*
>>>> * Remove this CPU:
>>>> */
>>>> + set_cpu_active(smp_processor_id(), false);
>>>> set_cpu_online(smp_processor_id(), false);
>>>> disable_local_APIC();
>>>> mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
>>>>
>>> No luck. The problem is still seen with this patch applied on top of
>>> the mainline kernel (commit a69e90512d9def6).
>>
>> Yeah, was a bit too naive ....
>>
>> We actually need to do the full cpuhotplug dance for a regular
>> reboot. In the panic case, there is nothing we can do about. I'll
>> have a look tomorrow.
>>

What is supposed to prevent the following in mainline:

CPU 0 CPU 1 CPU 2

native_stop_other_cpus <INTERRUPT>
send_IPI_allbutself ...
<INTERRUPT>
sysvec_reboot
stop_this_cpu
set_cpu_online(false)
native_smp_send_reschedule(1)
if (cpu_is_offline(1)) ...

Jan

--
Siemens AG, T RDA IOT
Corporate Competence Center Embedded Linux

\
 
 \ /
  Last update: 2021-07-27 10:47    [W:0.090 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site