Re: [RFC PATCH v5 mm-new 5/5] selftest/bpf: add selftest for BPF based THP order seletection

[Usama Arif <usamaarif642@gmail.com>]

On 18/08/2025 06:55, Yafang Shao wrote:
> This self-test verifies that PMD-mapped THP allocation is restricted in
> page faults for tasks within a specific cgroup, while still permitting
> THP allocation via khugepaged.
> 
> Since THP allocation depends on various factors (e.g., system memory
> pressure), using the actual allocated THP size for validation is
> unreliable. Instead, we check the return value of get_suggested_order(),
> which indicates whether the system intends to allocate a THP, regardless of
> whether the allocation ultimately succeeds.
> 
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> ---
>  tools/testing/selftests/bpf/config            |   3 +
>  .../selftests/bpf/prog_tests/thp_adjust.c     | 224 ++++++++++++++++++
>  .../selftests/bpf/progs/test_thp_adjust.c     |  76 ++++++
>  .../bpf/progs/test_thp_adjust_failure.c       |  25 ++
>  4 files changed, 328 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/thp_adjust.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_thp_adjust.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_thp_adjust_failure.c
> 

I think would be good to add selftests to make sure the bpf programs are working
after fork/exec as intended.