Message-ID: <c75e3b34-f4c0-ea1f-6447-6da623d9c951@huawei.com>
Date:   Wed, 16 Oct 2019 20:07:00 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     Peter Zijlstra <peterz@...radead.org>,
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Subject: Re: [PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware

On 2019/10/16 0:58, Greg KH wrote:
> On Tue, Oct 15, 2019 at 06:40:29PM +0800, Yunsheng Lin wrote:
>> On 2019/10/14 17:25, Greg KH wrote:
>>> On Mon, Oct 14, 2019 at 04:00:46PM +0800, Yunsheng Lin wrote:
>>>> On 2019/10/12 18:47, Greg KH wrote:
>>>>> On Sat, Oct 12, 2019 at 12:40:01PM +0200, Greg KH wrote:
>>>>>> On Sat, Oct 12, 2019 at 05:47:56PM +0800, Yunsheng Lin wrote:
>>>>>>> On 2019/10/12 15:40, Greg KH wrote:
>>>>>>>> On Sat, Oct 12, 2019 at 02:17:26PM +0800, Yunsheng Lin wrote:
>>>>>>>>> add pci and acpi maintainer
>>>>>>>>> cc linux-pci@...r.kernel.org and linux-acpi@...r.kernel.org
>>>>>>>>>
>>>>>>>>> On 2019/10/11 19:15, Peter Zijlstra wrote:
>>>>>>>>>> On Fri, Oct 11, 2019 at 11:27:54AM +0800, Yunsheng Lin wrote:
>>>>>>>>>>> But I failed to see why the above is related to making node_to_cpumask_map()
>>>>>>>>>>> NUMA_NO_NODE aware?
>>>>>>>>>>
>>>>>>>>>> Your initial bug is for hns3, which is a PCI device, which really _MUST_
>>>>>>>>>> have a node assigned.
>>>>>>>>>>
>>>>>>>>>> It not having one, is a straight up bug. We must not silently accept
>>>>>>>>>> NO_NODE there, ever.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I suppose you mean reporting a lack of affinity when the node of a pcie
>>>>>>>>> device is not set by "not silently accept NO_NODE".
>>>>>>>>
>>>>>>>> If the firmware of a pci device does not provide the node information,
>>>>>>>> then yes, warn about that.
>>>>>>>>
>>>>>>>>> As Greg has asked about in [1]:
>>>>>>>>> what is a user to do when the user sees the kernel reporting that?
>>>>>>>>>
>>>>>>>>> We may tell user to contact their vendor for info or updates about
>>>>>>>>> that when they do not know about their system well enough, but their
>>>>>>>>> vendor may get away with this by quoting ACPI spec as the spec
>>>>>>>>> considering this optional. Should the user believe this is indeed a
>>>>>>>>> fw bug or a misreport from the kernel?
>>>>>>>>
>>>>>>>> Say it is a firmware bug, if it is a firmware bug, that's simple.
>>>>>>>>
>>>>>>>>> If this kind of reporting is common pratice and will not cause any
>>>>>>>>> misunderstanding, then maybe we can report that.
>>>>>>>>
>>>>>>>> Yes, please do so, that's the only way those boxes are ever going to get
>>>>>>>> fixed.  And go add the test to the "firmware testing" tool that is based
>>>>>>>> on Linux that Intel has somewhere, to give vendors a chance to fix this
>>>>>>>> before they ship hardware.
>>>>>>>>
>>>>>>>> This shouldn't be a big deal, we warn of other hardware bugs all the
>>>>>>>> time.
>>>>>>>
>>>>>>> Ok, thanks for clarifying.
>>>>>>>
>>>>>>> Will send a patch to catch the case when a pcie device without numa node
>>>>>>> being set and warn about it.
>>>>>>>
>>>>>>> Maybe use dev->bus to verify if it is a pci device?
>>>>>>
>>>>>> No, do that in the pci bus core code itself, when creating the devices
>>>>>> as that is when you know, or do not know, the numa node, right?
>>>>>>
>>>>>> This can't be in the driver core only, as each bus type will have a
>>>>>> different way of determining what the node the device is on.  For some
>>>>>> reason, I thought the PCI core code already does this, right?
>>>>>
>>>>> Yes, pci_irq_get_node(), which NO ONE CALLS!  I should go delete that
>>>>> thing...
>>>>>
>>>>> Anyway, it looks like the pci core code does call set_dev_node() based
>>>>> on the PCI bridge, so if that is set up properly, all should be fine.
>>>>>
>>>>> If not, well, you have buggy firmware and you need to warn about that at
>>>>> the time you are creating the bridge.  Look at the call to
>>>>> pcibus_to_node() in pci_register_host_bridge().
>>>>
>>>> Thanks for pointing out the specific function.
>>>> Maybe we do not need to warn about the case when the device has a parent,
>>>> because we must have warned about the parent if the device has a parent
>>>> and the parent also has a node of NO_NODE, so do not need to warn the child
>>>> device anymore? like blew:
>>>>
>>>> @@ -932,6 +932,10 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
>>>>         list_add_tail(&bus->node, &pci_root_buses);
>>>>         up_write(&pci_bus_sem);
>>>>
>>>> +       if (nr_node_ids > 1 && !parent &&
>>>
>>> Why do you need to check this?  If you have a parent, it's your node
>>> should be set, if not, that's an error, right?
>>
>> If the device has parent and the parent device also has a node of
>> NUMA_NO_NODE, then maybe we have warned about the parent device, so
>> we do not have to warn about the child device?
> 
> But it's a PCI bridge, if it is not set properly, that needs to be fixed
> otherwise the PCI devices attached to it have no hope of working
> properly.

You may be right, thanks.

If it's a root PCI bridge and it does have a parent device, but
the parent device is not a pcie device and it's node is NUMA_NO_NODE,
then we will miss warning about this case.

> 
>> In pci_register_host_bridge():
>>
>> 	if (!parent)
>> 		set_dev_node(bus->bridge, pcibus_to_node(bus));
>>
>> The above only set the node of the bridge device to the node of bus if
>> the bridge device does not have a parent.
> 
> Odd, what happens to devices behind another bridge today?  Are their
> nodes set properly today?  Is the node supposed to be the same as the
> parent bridge?

It seems only the root bridge is added in pci_register_host_bridge(),
and other bridges under the root bridge is added in pci_alloc_child_bus().

And in pci_alloc_child_bus(), the child bus device is setup with proper
parent, so the pcie device under the child bus should have the same node
as the parent bridge when device_add() is called, which will set the node
to its parent's node when the child device' node is NUMA_NO_NODE.

Do not have a system with multi bridges at hand to debug it, so I may
be wrong about above.

> 
>>>> +           dev_to_node(bus->bridge) == NUMA_NO_NODE)
>>>> +               dev_err(bus->bridge, FW_BUG "No node assigned on NUMA capable HW. Please contact your vendor for updates.\n");
>>>> +
>>>>         return 0;
>>>
>>> Who set that bus->bridge node to NUMA_NO_NODE?
>>
>> It seems x86 and arm64 may have different implemention of
>> pcibus_to_node():
>>
>> For arm64:
>> int pcibus_to_node(struct pci_bus *bus)
>> {
>> 	return dev_to_node(&bus->dev);
>> }
>>
>> And the node of bus is set in:
>> int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
>> {
>> 	if (!acpi_disabled) {
>> 		struct pci_config_window *cfg = bridge->bus->sysdata;
>> 		struct acpi_device *adev = to_acpi_device(cfg->parent);
>> 		struct device *bus_dev = &bridge->bus->dev;
>>
>> 		ACPI_COMPANION_SET(&bridge->dev, adev);
>> 		set_dev_node(bus_dev, acpi_get_node(acpi_device_handle(adev)));
>> 	}
>>
>> 	return 0;
>> }
>>
>> acpi_get_node() may return NUMA_NO_NODE in pcibios_root_bridge_prepare(),
>> which will set the node of bus_dev to NUMA_NO_NODE
>>
>>
>> x86:
>> static inline int __pcibus_to_node(const struct pci_bus *bus)
>> {
>> 	const struct pci_sysdata *sd = bus->sysdata;
>>
>> 	return sd->node;
>> }
>>
>> And the node of bus is set in pci_acpi_scan_root(), which uses
>> pci_acpi_root_get_node() get the node of a bus. And it also may return
>> NUMA_NO_NODE.
> 
> Fixing that will be good :)>
>>> If that is set, the firmware is broken, as you say, but you need to tell
>>> the user what firmware is broken.
>>
>> Maybe mentioning the BIOS in log?
>> dev_err(bus->bridge, FW_BUG "No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.\n");
> 
> That's a good start.  Try running it on your machines (big and small)
> and see what happens.

There is no fw bug log output as above when using newer bios(
which has provided the device node through ACPI) in my machine.

> 
>>> Try something like this out and see what happens on your machine that
>>> had things "broken".  What does it say?
>>
>> Does not have a older bios right now.
>> But always returning NUMA_NO_NODE by below patch:
>>
>> --- a/drivers/acpi/numa.c
>> +++ b/drivers/acpi/numa.c
>> @@ -484,6 +484,7 @@ int acpi_get_node(acpi_handle handle)
>>
>>         pxm = acpi_get_pxm(handle);
>>
>> -       return acpi_map_pxm_to_node(pxm);
>> +       return -1;
>> +       //return acpi_map_pxm_to_node(pxm);
>>
>> it gives the blow warning in my machine:
>>
>> [   16.126136]  pci0000:00: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   17.733831]  pci0000:7b: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   18.020924]  pci0000:7a: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   18.552832]  pci0000:78: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   19.514948]  pci0000:7c: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   20.652990]  pci0000:74: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   22.573200]  pci0000:80: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   23.225355]  pci0000:bb: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   23.514040]  pci0000:ba: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   24.050107]  pci0000:b8: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   25.017491]  pci0000:bc: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
>> [   25.557974]  pci0000:b4: [Firmware Bug]: No node assigned on NUMA capable HW by BIOS. Please contact your vendor for updates.
> 
> And can you fix your bios?  If you can't then why are we going to warn
> about this?

Yes, our new bios has fixed that.

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