Re: [PATCH v5 3/4] selftest/mm: test enable_soft_offline behaviors

[Miaohe Lin <linmiaohe@huawei.com>]

On 2024/6/26 7:57, Jiaqi Yan wrote:
> On Tue, Jun 25, 2024 at 12:05 AM Miaohe Lin <linmiaohe@huawei.com> wrote:
>>
>> On 2024/6/25 0:33, Jiaqi Yan wrote:
>>> Add regression and new tests when hugepage has correctable memory
>> ...
>>> diff --git a/tools/testing/selftests/mm/hugetlb-soft-offline.c b/tools/testing/selftests/mm/hugetlb-soft-offline.c
>>> new file mode 100644
>>> index 000000000000..16fe52f972e2
>>> --- /dev/null
>>> +++ b/tools/testing/selftests/mm/hugetlb-soft-offline.c
>>> @@ -0,0 +1,227 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Test soft offline behavior for HugeTLB pages:
>>> + * - if enable_soft_offline = 0, hugepages should stay intact and soft
>>> + *   offlining failed with EINVAL.
>>
>> s/failed with EINVAL/failed with EOPNOTSUPP/g
> 
> To be fixed in v6.
> 
>>
>>> + * - if enable_soft_offline = 1, a hugepage should be dissolved and
>>> + *   nr_hugepages/free_hugepages should be reduced by 1.
>>> + *
>>> + * Before running, make sure more than 2 hugepages of default_hugepagesz
>>> + * are allocated. For example, if /proc/meminfo/Hugepagesize is 2048kB:
>>> + *   echo 8 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
>>> + */
>>> +
>> ...
>>> +static void test_soft_offline_common(int enable_soft_offline)
>>> +{
>>> +     int fd;
>>> +     int expect_errno = enable_soft_offline ? 0 : EOPNOTSUPP;
>>> +     struct statfs file_stat;
>>> +     unsigned long hugepagesize_kb = 0;
>>> +     unsigned long nr_hugepages_before = 0;
>>> +     unsigned long nr_hugepages_after = 0;
>>> +     int ret;
>>> +
>>> +     ksft_print_msg("Test soft-offline when enabled_soft_offline=%d\n",
>>> +                    enable_soft_offline);
>>> +
>>> +     fd = create_hugetlbfs_file(&file_stat);
>>> +     if (fd < 0) {
>>> +             ksft_exit_fail_msg("Failed to create hugetlbfs file\n");
>>> +             return;
>>> +     }
>>> +
>>> +     hugepagesize_kb = file_stat.f_bsize / 1024;
>>> +     ksft_print_msg("Hugepagesize is %ldkB\n", hugepagesize_kb);
>>> +
>>> +     if (set_enable_soft_offline(enable_soft_offline)) {
>>> +             ksft_exit_fail_msg("Failed to set enable_soft_offline\n");
>>
>> Call destroy_hugetlbfs_file() in error path?
> 
> As the counterpart of destroy_hugetlbfs_file, I think the test only
> needs to close(fd). Will add it in v6.
> 
>>
>>> +             return;
>>> +     }
>>> +
>>> +     if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_before) != 0) {
>>> +             ksft_exit_fail_msg("Failed to read nr_hugepages\n");
>>> +             return;
>>> +     }
>>> +
>>> +     ksft_print_msg("Before MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
>>> +                    nr_hugepages_before);
>>> +
>>> +     ret = do_soft_offline(fd, 2 * file_stat.f_bsize, expect_errno);
>>> +
>>> +     if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_after) != 0) {
>>> +             ksft_exit_fail_msg("Failed to read nr_hugepages\n");
>>> +             return;
>>> +     }
>>> +
>>> +     ksft_print_msg("After MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
>>> +             nr_hugepages_after);
>>> +
>>> +     if (enable_soft_offline) {
>>> +             if (nr_hugepages_before != nr_hugepages_after + 1) {
>>> +                     ksft_test_result_fail("MADV_SOFT_OFFLINE should reduced 1 hugepage\n");
>>> +                     return;
>>> +             }
>>> +     } else {
>>> +             if (nr_hugepages_before != nr_hugepages_after) {
>>> +                     ksft_test_result_fail("MADV_SOFT_OFFLINE reduced %lu hugepages\n",
>>> +                             nr_hugepages_before - nr_hugepages_after);
>>> +                     return;
>>> +             }
>>> +     }
>>> +
>>> +     ksft_test_result(ret == 0,
>>> +                      "Test soft-offline when enabled_soft_offline=%d\n",
>>> +                      enable_soft_offline);
>>
>> Call destroy_hugetlbfs_file() when test finished ?
> 
> Test can just close(fd) once nr_hugepages_after is read.

I'm sorry but I can't find the code to call close(fd) after nr_hugepages_after is read.
IMO create_hugetlbfs_file() would fail to create a new hugetlb file later if close(fd)
is not called when testing previous enable_soft_offline = 1 testcase. Because a hugetlb
file with same name is already there. But I might miss something.

Thanks.
.