Re: Kunit test failures with cpumask tests on parisc

[Guenter Roeck]

On 2/5/24 01:28, Helge Deller wrote:
> On 2/5/24 07:53, Guenter Roeck wrote:
> > when running cpumask Kunit tests on parisc/parisc64 in qemu,
> > I get the following errors.
> >
> >        KTAP version 1
> >        # Subtest: cpumask
> >        # module: cpumask_kunit
> >        1..6
> >        # test_cpumask_weight: EXPECTATION FAILED at lib/cpumask_kunit.c:68
> >        Expected nr_cpu_ids == cpumask_weight(((const struct cpumask *)&__cpu_possible_mask)), but
> >            nr_cpu_ids == 16 (0x10)
> >            cpumask_weight(((const struct cpumask *)&__cpu_possible_mask)) == 1 (0x1)
> >    cpu_possible_mask contains CPUs 0
> >        not ok 1 test_cpumask_weight
> >        # test_cpumask_first: EXPECTATION FAILED at lib/cpumask_kunit.c:79
> >        Expected nr_cpu_ids <= cpumask_first_zero(((const struct cpumask *)&__cpu_possible_mask)), but
> >            nr_cpu_ids == 16 (0x10)
> >            cpumask_first_zero(((const struct cpumask *)&__cpu_possible_mask)) == 1 (0x1)
> >    cpu_possible_mask contains CPUs 0
> >        not ok 2 test_cpumask_first
> >        # test_cpumask_last: EXPECTATION FAILED at lib/cpumask_kunit.c:87
> >        Expected nr_cpu_ids - 1 == cpumask_last(((const struct cpumask *)&__cpu_possible_mask)), but
> >            nr_cpu_ids - 1 == 15 (0xf)
> >            cpumask_last(((const struct cpumask *)&__cpu_possible_mask)) == 0 (0x0)
> >    cpu_possible_mask contains CPUs 0
> >        not ok 3 test_cpumask_last
> >        # test_cpumask_next: EXPECTATION FAILED at lib/cpumask_kunit.c:94
> >        Expected nr_cpu_ids <= cpumask_next_zero(-1, ((const struct cpumask *)&__cpu_possible_mask)), but
> >            nr_cpu_ids == 16 (0x10)
> >            cpumask_next_zero(-1, ((const struct cpumask *)&__cpu_possible_mask)) == 1 (0x1)
> >    cpu_possible_mask contains CPUs 0
> >        not ok 4 test_cpumask_next
> >        ok 5 test_cpumask_iterators
> >        ok 6 test_cpumask_iterators_builtin
> >    # cpumask: pass:2 fail:4 skip:0 total:6
> >    # Totals: pass:2 fail:4 skip:0 total:6
> >    not ok 5 cpumask
> >
> > It appears that parisc sets __cpu_possible_mask to the number of online CPUs,
> > which is limited in qemu and doesn't match CONFIG_NR_CPUS. Is this a problem
> > with the unit test or with the parisc architecture, or does the unit test
> > simply not apply for parisc ?
>
> Thank you for finding and reporting this!
> It's a bug (or a misunderstanding) in the parisc kernel.
> Reverting commit 0921244f6f4f ("parisc: Only list existing CPUs in cpu_possible_mask")
> fixes the KUnit test.
>
> Furthermore the revert fixes the issue that CPU hot-unplugging doesn't
> work and which I just was starting to debug:
> https://lore.kernel.org/lkml/Zb0mbHlIud_bqftx@xxxxxxxxxxxxxxx/t/

Glad to help, and thanks for the update.

Guenter