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Date:   Tue, 27 Jul 2021 10:00:18 +0200
From:   Henning Schild <henning.schild@siemens.com>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Guenter Roeck <linux@roeck-us.net>,
        Peter Zijlstra <peterz@infradead.org>, <x86@kernel.org>,
        Ingo Molnar <mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
        Borislav Petkov <bp@alien8.de>, xenomai@xenomai.org
Subject: Re: sched: Unexpected reschedule of offline CPU#2!
Message-ID: <20210727100018.19d61165@md1za8fc.ad001.siemens.net>
In-Reply-To: <alpine.DEB.2.21.1908172219470.1923@nanos.tec.linutronix.de>
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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.

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.
> 
> Thanks,
> 
> 	tglx