Re: [PATCH v2] lib/sbitmap: add KUnit test suite

[Keith Teeple <keithrteeple@gmail.com>]

On Fri, 16 Oct 2026 15:32:53 +0800, Wang Yibo wrote:
> v2:
>  - Test sb.alloc_hint as a plain boolean: KUNIT_EXPECT_NOT_NULL() passes
>    its argument through a const void *, which a __percpu pointer cannot do
>    on architectures that keep percpu data in a separate address space, so
>    the test did not build on x86 (David Gow).
>  - Use a BITS_PER_LONG-relative bit number in sbitmap_test_iterate_set().
>    The hardcoded 130 lies past the end of the test bitmap when
>    BITS_PER_LONG is 32, so that bit was never visited and the test failed;
>    assert the precondition while at it (David Gow).

I am new here and trying to be helpful by testing others' patches. I
reproduced both v1 failures and confirmed the v2 fixes, applied on the
stated base (4056b3c9d3c9) and built with gcc 16.2.1:

  - x86_64 under QEMU: v1 fails to build at sbitmap_kunit.c:38,
    same as you saw with gcc 15.2. v2 builds and passes 8/8.

    One detail: this needs CONFIG_SMP=y as well as
    CONFIG_USE_X86_SEG_SUPPORT=y. Without SMP, __percpu has no address space and v1
    builds and passes. The kunit.py x64_64 QEMU config leaves SMP off by default.

  - i386 under QEMU: v1 fails sbitmap_test_iterate_set with
    nr_visited == 5 (expected 6). v2 passes 8/8.

  - UML: v2 passes 8/8.

Tested-by: Keith Teeple <keithrteeple@gmail.com>