Re: [Bugfix] x86/PCI: Fix regression caused by commit 4d6b4e69a245

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
To: Jiang Liu <jiang.liu@linux.intel.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Bjorn Helgaas <helgaas@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	x86@kernel.org, Keith Busch <keith.busch@intel.com>,
	Arthur Marsh <arthur.marsh@internode.on.net>
Subject: Re: [Bugfix] x86/PCI: Fix regression caused by commit 4d6b4e69a245
Date: Wed, 25 Nov 2015 14:11:46 +0100	[thread overview]
Message-ID: <5655B392.7070701@intel.com> (raw)
In-Reply-To: <56556D89.6020801@linux.intel.com>

On 11/25/2015 9:12 AM, Jiang Liu wrote:
> On 2015/11/25 6:19, Rafael J. Wysocki wrote:
>> On Tue, Nov 24, 2015 at 5:49 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
>>> On Mon, Nov 16, 2015 at 12:27:37PM +0800, Jiang Liu wrote:
>>>> From: Liu Jiang <jiang.liu@linux.intel.com>
>>>>
>>>> Commit 4d6b4e69a245 ("x86/PCI/ACPI: Use common interface to support
>>>> PCI host bridge") converted x86 to use the common interface
>>>> acpi_pci_root_create, but the conversion missed on code piece in
>>>> arch/x86/pci/bus_numa.c, which causes regression on some legacy
>>>> AMD platforms as reported by Arthur Marsh <arthur.marsh@internode.on.net>.
>>>> The root causes is that acpi_pci_root_create() fails to insert
>>>> host bridge resources into iomem_resource/ioport_resource because
>>>> x86_pci_root_bus_resources() has already inserted those resources.
>>>> So change x86_pci_root_bus_resources() to not insert resources into
>>>> iomem_resource/ioport_resource.
>>> Fixes: 4d6b4e69a245 ("x86/PCI/ACPI: Use common interface to support PCI host bridge")
>>>
>>>> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
>>>> Reported-and-tested-by: Arthur Marsh <arthur.marsh@internode.on.net>
>>> What's the status of this?  It looks like a regression we need to fix
>>> for v4.4.
>>>
>>> AFAICT, Arthur did *not* test this patch (rather, his response says he
>>> did test it and the test failed).
>>>
>>> 4d6b4e69a245 was merged by Rafael, and I assume he'll merge the fix
>>> unless I hear otherwise.
>> Quite frankly, I'm more likely to revert the offending commit at this
>> point as that's not the only regression reported against it and the
>> fix only helps in one case (out of three known to me).
> Hi Rafael,
> 	I got regression report from Hans de Bruin<jmdebruin@xmsnet.nl>,
> Keith Busch <keith.busch@intel.com>, and Arthur Marsh
> <arthur.marsh@internode.on.net>. Hans and Keith also reports
> the patch fixes the regression. For Arthur's case, the debug
> patch works for him, but the formal patch based on the debug
> patch fails, so I need to do more investigation about this.
> Is there any other report related to commit 4d6b4e69a245 so
> I could help to investigate?

OK, so the proposed bug fix works for everybody, right?

In that case there's no reason not to apply it.

If there's anyone who can reproduce the problem and for whom that patch 
doesn't work, please let me know.

Thanks,
Rafael