Bug 201127

On Fri, Sep 14, 2018 at 09:28:27AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=201127
> 
>             Bug ID: 201127
>            Summary: [REGRESSION][BISECTED] Boot stall related to
>                     drivers/pci/hotplug/acpiphp_glue.c
>            Product: Drivers
>            Version: 2.5
>     Kernel Version: 4.18

All USB bugs should be sent to the linux-usb@vger.kernel.org mailing
list, and not entered into bugzilla.  Please bring this issue up there,
if it is still a problem in the latest kernel release.

Okay, thanks. I had no idea of this being an USB bug.

The MAINTAINERS file has this section in it: 

ACPI
M:	"Rafael J. Wysocki" <rjw@rjwysocki.net>
M:	Len Brown <lenb@kernel.org>
L:	linux-acpi@vger.kernel.org
W:	https://01.org/linux-acpi
Q:	https://patchwork.kernel.org/project/linux-acpi/list/
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
B:	https://bugzilla.kernel.org
S:	Supported
F:	drivers/acpi/
F:	drivers/pnp/pnpacpi/
F:	include/linux/acpi.h
F:	include/linux/fwnode.h
F:	include/acpi/
F:	Documentation/acpi/
F:	Documentation/ABI/testing/sysfs-bus-acpi
F:	Documentation/ABI/testing/configfs-acpi
F:	drivers/pci/*acpi*
F:	drivers/pci/*/*acpi*
F:	drivers/pci/*/*/*acpi*
F:	tools/power/acpi/

That's why I entered this to Bugzilla. The product might need to be changed to ACPI though.

On Fri, Sep 14, 2018 at 10:51:10AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=201127
> 
> --- Comment #2 from Peter Anemone (peter.anemone@gmail.com) ---
> Okay, thanks. I had no idea of this being an USB bug.

Sorry, it isn't, my scripts just triggered the response, sorry.

It's a PCI issue, please reassign to the PCI component and email the
linux-pci@vger.kernel.org list.

Created attachment 278583 [details]
First fix attempt

Could you try the attached patch and see if it helps? If not can you next try to comment out the following lines (with the patch applied) in drivers/pci/hotplug/acpiphp_glue.c::enable_slot()?

//  if (bus->self->subordinate)
//          pci_assign_unassigned_bridge_resources(bus->self);

In addition, can you attach output of 'sudo lspci -vv' and acpidump from the working kernel?

Sorry did not notice that you already have lspci output in the tar file you attached. So only acpidump then :)

Created attachment 278619 [details]
acpidump

Commenting out the requested lines worked (and the patch didn't work without commenting them):

//  if (bus->self->subordinate)
//          pci_assign_unassigned_bridge_resources(bus->self);

Here's an acpidump from the patched kernel 4.19-rc4

Created attachment 278621 [details]
Add more debugging to ACPI hotplug and skip resource distribution

Could you try this patch instead? Please attach full dmesg as well (assuming your system does not crash).

Created attachment 278625 [details]
dmesg

Here's dmesg from the previous patched kernel.

The new patch did not work.

Hi, can you do so that you keep the last patch applied but comment out the line:

  pci_assign_unassigned_bridge_resources(bus->self);

in drivers/pci/hotplug/acpiphp_glue.c::enable_slot() just like you did previosly and then attach full dmesg? It should show when the ACPI hotplug event happens.

Created attachment 278627 [details]
new dmesg

(In reply to Mika Westerberg from comment #10)
> Hi, can you do so that you keep the last patch applied but comment out the
> line:
> 
>   pci_assign_unassigned_bridge_resources(bus->self);
> 
> in drivers/pci/hotplug/acpiphp_glue.c::enable_slot() just like you did
> previosly and then attach full dmesg? It should show when the ACPI hotplug
> event happens.

Did that, here's the output of dmesg

Thanks. It looks like the ACPI notify (bus check) comes to the NIC:

[    0.942239] ACPI: \_SB_.PCI0.RP06.NIC_: Bus check in hotplug_event()

and I think enable_slot() in acpiphp_glue.c should not treat it as "ACPI hotplug to native PCIe hotplug port" special case here.

Created attachment 278629 [details]
Third fix attempt

Can you try the attached patch and see if it works? Please attach dmesg again.

Created attachment 278631 [details]
dmesg after third patch

Here's new dmesg for the latest patch. It worked.

Thanks for testing. I'll submit a proper patch upstream shortly.

Marking this resolved as the patch is included in 4.19-rc6 and in the stable-queue.

Thank you Mika :)
(and all the others involved)