Re: [PATCH] drivers/base/node: Handle error properly in register_one_node()

Donet Tom
2025-07-02T13:00:20Z

On 7/2/25 6:16 PM, Oscar Salvador wrote:
> On Wed, Jul 02, 2025 at 06:28:56AM -0500, Donet Tom wrote:
>> If register_node() returns an error, it is not handled correctly.
>> The function will proceed further and try to register CPUs under the
>> node, which is not correct.
>>
>> So, in this patch, if register_node() returns an error, we return
>> immediately from the function.
>>
>> Signed-off-by: Donet Tom <donettom@linux.ibm.com>
>> ---
>>
> ...
>> diff --git a/drivers/base/node.c b/drivers/base/node.c
>> index bef84f01712f..aec991b4c0b2 100644
>> --- a/drivers/base/node.c
>> +++ b/drivers/base/node.c
>> @@ -885,6 +885,8 @@ int register_one_node(int nid)
>> node_devices[nid] = node;
>>
>> error = register_node(node_devices[nid], nid);
>> + if (error)
>> + return error;
> Ok, all current callers (based on mm-unstable) panic or BUG() if this fails,
> but powerpc, in init_phb_dynamic(), which keeps on going.
> Unless it panics somewhere down the road as well.
>
> So I think we need to:
>
> node_devices[nid] = NULL
> kfree(node)
>
> ?

Yes, I will add this too.

But one question: if register_node() fails, is it okay to continue, or
should we panic?

What is the correct way to handle this?

> Also, once Hannes fix lands, we might need that as well.
>
> Anyway, I'd suggest you hold on until Hannes fix lands, so we can later
> rebase all your mem-hotplug on top of that [1].

Sure

>
> [1] https://lore.kernel.org/linux-mm/86f89a65-f0f6-4462-9eea-ac691de2f3b6@suse.de/T/#mbf392eb390b8053f96be50da3b40dfd9b62dd389
>
>