Re: [PATCH bpf-next v7 0/9] Introduce arena library and runtime

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

On Sun Apr 12, 2026 at 3:22 PM EDT, Kumar Kartikeya Dwivedi wrote:
> On Sun, 12 Apr 2026 at 19:45, Emil Tsalapatis <emil@etsalapatis.com> wrote:
>>
>> Add a new subdirectory to tools/testing/selftests/bpf called libarena,
>> along with programs useful for writing arena-based BPF code. This
>> patchset adds the following:
>>
>> 1) libarena, a subdirectory where arena BPF code that is generally useful
>> to BPF arena programs can be easily added and tested.
>>
>> 2) An ASAN runtime for BPF arena programs. BPF arenas allow for accessing
>> memory after it has been freed or if it is out of bounds, making it more
>> difficult to triage bugs combined to regular BPF. Use LLVM's recently added
>> support for address-space based sanitization to selectively sanitize just
>> the arena accesses.
>>
>> 3) A buddy memory allocator that can be reused by BPF programs to handle
>> memory allocation/deletion. The allocator uses the ASAN runtime to add
>> address sanitization if requested.
>>
>> The patch includes testing for the new allocators and ASAN features that
>> can be built from the top directory using "make libarena_test" and
>> "make libarena_test_asan". The generated binaries reside in libarena/.
>> The patch also adds test-progs-based selftests to the codebase for the
>> libarena code, so the new tests are run by ./test_progs.
>>
>
> I am back in the same position as I was with comments in [0].
>
> I.e., again, I don't see anything in the stream output (passing -v to
> test_libarena_asan) when I build it with clang 23 (LLVM tip).
> What am I doing wrong? (Leaving aside all feedback about integrating
> it in the regular test runner that is still unaddressed, thus tests do
> not run by default).
>
>   [0]: https://lore.kernel.org/bpf/CAP01T75+BoQfQN=47NhYYviZttjCPb_CXNpa=DUC0=xSvdNZdA@mail.gmail.com

The series introduces a selftest for the test runner called libarena. It
is introduced in patch 9 to avoid creating a runner that does nothing in
the previous patches. Tests run with test_progs like regular selftests.
For ASAN we do not have LLVM22 support in the CI yet so test_progs doesn't
exercise it.

The stream output is suppressed by a switch in asan.c to make the output
of test_libarena_asan legible. Each test that expects to generate ASAN
will generate a ton of output. I will add userspace logic to consume 
the splats instead of emitting them to keep the output sane.

>
>> [...]