Re: [PATCH bpf-next v13 8/8] selftests/bpf: Add tests to verify map create failure log

[Leon Hwang <leon.hwang@linux.dev>]

On 2026/5/14 00:58, Alexei Starovoitov wrote:
> On Wed, May 13, 2026 at 3:47 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>> On 13/5/26 08:33, sashiko-bot@kernel.org wrote:
>> [...]
>>>> +static void test_invalid_numa_node(void)
>>>> +{
>>>> +    const char *msg = "Invalid numa_node.\n";
>>>> +    LIBBPF_OPTS(bpf_map_create_opts, opts,
>>>> +                .map_flags = BPF_F_NUMA_NODE,
>>>> +                .numa_node = 0xFF,
>>>
>>> Is it possible for this test to fail spuriously on large systems? If the
>>> test runs on a machine with 256 or more NUMA nodes where node 255 is
>>> online, the kernel validation will pass.
>>>
>>> The map creation might then fail for another reason, skipping the expected
>>> log message and causing the test to fail.
>>>
>>> Would a value like 0xFFFFFFFE (avoiding NUMA_NO_NODE) be more reliable to
>>> ensure it exceeds nr_node_ids?
>>>
>>
>> Practically, NUMA nodes number wouldn't be >=255.
>>
>> Instead of 0xFFFFFFFE, better to get possible numa node number from
>> /sys/devices/system/node/possible, like libbpf_num_possible_cpus() to
>> get possible cpu number.
> 
> Ignore this bit. There won't be such numa nodes any time soon.

Get it.

Thanks,
Leon