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Message-ID: <c1d89da0-f9ef-44d8-8731-5a34240eba95@roeck-us.net>
Date: Mon, 5 Feb 2024 08:06:03 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Helge Deller <deller@....de>, Yury Norov <yury.norov@...il.com>
Cc: James.Bottomley@...senpartnership.com, linux-parisc@...r.kernel.org,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>, linux-kernel@...r.kernel.org
Subject: Re: Kunit test failures with cpumask tests on parisc
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@slm.duckdns.org/t/
>
Glad to help, and thanks for the update.
Guenter
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