Re: Linux 5.3-rc7
From: Thomas Gleixner
Date: Sat Sep 07 2019 - 16:14:31 EST
On Sat, 7 Sep 2019, Chris Wilson wrote:
> Quoting Thomas Gleixner (2019-09-07 16:00:17)
> > 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.
> If I ignore cpu0 in that test and so use
> [ 133.847187] smpboot: CPU 1 is now offline
> [ 134.861861] x86: Booting SMP configuration:
> [ 134.861875] smpboot: Booting Node 0 Processor 1 APIC 0x2
> [ 134.880218] smpboot: CPU 2 is now offline
> [ 135.893806] smpboot: Booting Node 0 Processor 2 APIC 0x1
> [ 135.935115] smpboot: CPU 3 is now offline
> [ 136.949760] smpboot: Booting Node 0 Processor 3 APIC 0x3
> that has run for 10 minutes without failure, so it seems confined to
> cpu0 hotplugging. All we are doing in the test to generate the hotplugs
Right, but you also have that config bit enabled which allows CPU0 hotplug
which usually is off even in testing and that's why nobody noticed so far.
So I looked at that code and I know why it's broken. I guess we'll end up
reverting that commit for now as fixing it proper will be not just a one
Thanks for providing all the information!