Re: [PATCH bpf-next v2 5/9] selftests/bpf: Add kfunc __arena and __arena_nullable argument tests

On Sun Jul 26, 2026 at 3:41 AM CEST, sashiko-bot wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The `arena_arg_stack` failure test is conditionally compiled out on compilers missing `__BPF_FEATURE_ADDR_SPACE_CAST`, causing a false test suite failure.
> --
>
> --- Patch [5]: [PATCH bpf-next v2 5/9] selftests/bpf: Add kfunc __arena and __arena_nullable argument tests ---
> commit b7abeb2e41481276f90bb3144448d08e3c6e2c96
> Author: Tejun Heo <[email protected]>
>
> selftests/bpf: Add kfunc __arena and __arena_nullable argument tests
>
> This commit adds kfunc arena argument tests to bpf_testmod to exercise
> argument rebasing, various accepted argument forms, and verifier rejections.
>
>> diff --git a/tools/testing/selftests/bpf/progs/arena_kfunc.c b/tools/testing/selftests/bpf/progs/arena_kfunc.c
>> new file mode 100644
>> index 0000000000000..e7250c5197ab4
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/progs/arena_kfunc.c
>
> [ ... ]
>
>> +SEC("syscall")
>> +__arch_x86_64
>> +__failure __msg("arena pointer cannot be a stack argument")
>> +int arena_arg_stack(void *ctx)
>> +{
>> +#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
>> +	bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
>> +	bpf_kfunc_arena_stack_arg_test(1, 2, 3, 4, 5, (u64 *)1);
>> +#endif
>> +	return 0;
>> +}
>
> [Severity: Medium]
> Does this conditional compilation cause the test suite to fail on older
> compilers missing __BPF_FEATURE_ADDR_SPACE_CAST?
>
> Because this test is marked with __failure, the test runner expects the
> verifier to reject it. If the macro is not defined, the program compiles
> to just return 0. The verifier will successfully load the empty program,
> causing the test runner to report a failure because the expected rejection
> did not occur.

I think the goal is to not fail compilation, this is fine as a tradeoff.