Re: [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported

["Emil Tsalapatis" <emil@etsalapatis.com>]

On Fri Oct 9, 2026 at 1:49 AM UTC, Qiliang Yuan wrote:
> serial_test_libarena runs the test programs of libarena, whose buddy
> allocator serializes its operations with an arena spin lock.
>
> arena_spin_lock() fails with -EOPNOTSUPP on kernels built with more
> than 1024 possible CPUs, as distributions commonly configure them.
> buddy_init() reports that as -EINVAL, and every test then fails at
> arena_buddy_reset.
>
> Patch 1 makes buddy_init() return the error of the lock, patch 2 skips
> the tests when resetting the allocator fails with -EOPNOTSUPP.
>

If new kernels expect more than 1024 CPUs, we should update libarena and
arena_spin_lock() to support them instead of returning EOPNOTSUPP.

pw-bot: cr

> Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
> ---
> Qiliang Yuan (2):
>       selftests/bpf: Return the lock error from buddy_init() of libarena
>       selftests/bpf: Skip libarena on kernels with too many possible CPUs
>
>  tools/testing/selftests/bpf/libarena/src/buddy.bpf.c | 5 +++--
>  tools/testing/selftests/bpf/prog_tests/libarena.c    | 9 +++++++++
>  2 files changed, 12 insertions(+), 2 deletions(-)
> ---
> base-commit: e1d84a37cba984388988d2f1ddc84561413f0db2
> change-id: 20261009-selftests-bpf-libarena-nr-cpus-50fc5dd00fe2
>
> Best regards,