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Date:   Sat, 7 Sep 2019 17:00:17 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Chris Wilson <chris@chris-wilson.co.uk>
cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Bandan Das <bsd@redhat.com>
Subject: Re: Linux 5.3-rc7
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On Sat, 7 Sep 2019, Chris Wilson wrote:
> Quoting Thomas Gleixner (2019-09-07 15:29:19)
> > On Sat, 7 Sep 2019, Chris Wilson wrote:
> > > Quoting Linus Torvalds (2019-09-02 18:28:26)
> > > > Bandan Das:
> > > >       x86/apic: Include the LDR when clearing out APIC registers
> > > 
> > > Apologies if this is known already, I'm way behind on email.
> > > 
> > > I've bisected
> > > 
> > > [   18.693846] smpboot: CPU 0 is now offline
> > > [   19.707737] smpboot: Booting Node 0 Processor 0 APIC 0x0
> > > [   29.707602] smpboot: do_boot_cpu failed(-1) to wakeup CPU#0
> > > 
> > > https://intel-gfx-ci.01.org/tree/drm-tip/igt@perf_pmu@cpu-hotplug.html
> > > 
> > > to 558682b52919. (Reverts cleanly and fixes the problem.)
> > > 
> > > I'm guessing that this is also behind the suspend failures, missing
> > > /dev/cpu/0/msr, and random perf_event_open() failures we have observed
> > > in our CI since -rc7 across all generations of Intel cpus.
> > 
> > So is this on bare metal or in a VM?
> 
> Our single virtualised piece of kit doesn't support cpu hotplug, so this
> test is not being run. We have failures on
> icl (2019), glk (2017), kbl (2017), bxt (2016), skl (2015),
> bsw (2016), hsw (2013), byt (2013), snb (2011), elk (2008),
> bwr (2006), blb (2007)

Ok let me find a testbox to figure out whats wrong there.

Does this only happen with that CPU0 hotplug stuff enabled or on CPUs other
than CPU0 as well? That hotplug CPU0 stuff is a bandaid so I wouldn't be
surprised if we broke that somehow.

Thanks,

	tglx