Re: PROBLEM: 4.15.0-rc3 APIC causes lockups on Core 2 Duo laptop

From: Thomas Gleixner
Date: Tue Dec 19 2017 - 19:31:39 EST

On Tue, 19 Dec 2017, Alexandru Chirvasitu wrote:

> I had never heard of 'bisect' before this casual mention (you might tell
> I am a bit out of my depth). I've since applied it to Linus' tree between

> bebc608 Linux 4.14 (good)
> and
> 4fbd8d1 Linux 4.15-rc1 (bad)

Is Linus current head 4.15-rc4 bad as well?

> It took about 13 attempts (I had access to a faster machine to compile
> on, and ccache helped once the cache built up some momentum). The result
> is (as presented by 'git bisect' at the end of the process, between the
> --- dividers added by me for clarity):

> --- start of output ---
> 2b5175c4fa974b6aa05bbd2ee8d443a8036a1714 is the first bad commit
> commit 2b5175c4fa974b6aa05bbd2ee8d443a8036a1714
> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Date: Tue Oct 17 09:54:57 2017 +0200
> genirq: Add config option for reservation mode
> The interrupt reservation mode requires reactivation of PCI/MSI
> interrupts. Create a config option, so the PCI code can set the
> corresponding flag when required.
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Josh Poulson <jopoulso@xxxxxxxxxxxxx>
> Cc: Mihai Costache <v-micos@xxxxxxxxxxxxx>
> Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: linux-pci@xxxxxxxxxxxxxxx
> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Cc: Simon Xiao <sixiao@xxxxxxxxxxxxx>
> Cc: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
> Cc: Jork Loeser <Jork.Loeser@xxxxxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: devel@xxxxxxxxxxxxxxxxxxxxxx
> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>
> Link:
> :040000 040000 5e73031cc0c8411a20722cce7876ab7b82ed3858 dcf98e7a6b7d5f7c5353b7ccab02125e6d332ec8 M kernel
> --- end of output ---
> Consequently, I am cc-ing in the listed addresses.

Thanks for doing that bisect, but unfortunately this commit cannot be the
problematic one, It merily adds a config symbol, but it does not change any
code at all. It has no effect whatsoever. So something might have gone
wrong in your bisecting.

I CC'ed Dou Liyang. He has changed the early APIC setup code and there has
been an issue reported already. Though I lost track of that. Dou, any