On Thu, 25 Jun 2026 18:10:16 +0530 Sayali Patil <[email protected]> wrote:
> Some MM selftests attempt to configure the amount of
> HugeTLB pages of different sizes by writing to nr_hugepages.
>
> PowerPC hash MMU pSeries systems advertise gigantic hugepage sizes
> but do not support runtime allocation of such pages, writes
> to the corresponding nr_hugepages file fail with -EINVAL.
> This causes the test to bail out even though the failure is due
> to a platform limitation rather than the
> functionality being tested.
>
> Treat -EINVAL from the sysfs write as a skipped configuration request
> and continue running the test instead of failing.
>
> Before patch:
> -------------------------
> running ./hugetlb-madvise
> -------------------------
> TAP version 13
> 1..1
> [INFO] detected hugetlb page size: 16777216 KiB
> [INFO] detected hugetlb page size: 16384 KiB
> ok 1 MADV_DONTNEED and MADV_REMOVE on hugetlb
> Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> Bail out! /sys/kernel/mm/hugepages/hugepages-16777216kB/nr_hugepages
> write(0) failed: Invalid argument
> Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
> [FAIL]
>
> After patch:
> -------------------------
> running ./hugetlb-madvise
> -------------------------
> TAP version 13
> 1..1
> [INFO] detected hugetlb page size: 16777216 KiB
> [INFO] detected hugetlb page size: 16384 KiB
> ok 1 MADV_DONTNEED and MADV_REMOVE on hugetlb
> Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> /sys/kernel/mm/hugepages/hugepages-16777216kB/nr_hugepages
> write(0) failed: Invalid argument
> [PASS]
>
> Fixes: 9d07250ea1eb ("selftests/mm: hugepage_settings: add APIs to get and
> set nr_hugepages")
> Signed-off-by: Sayali Patil <[email protected]>
> ---
> tools/testing/selftests/mm/vm_util.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/tools/testing/selftests/mm/vm_util.c
> b/tools/testing/selftests/mm/vm_util.c
> index 311fc5b4513e..a8f16eef5c7c 100644
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -735,6 +735,13 @@ void write_file(const char *path, const char *buf,
> size_t buflen)
> saved_errno = errno;
> close(fd);
> errno = saved_errno;
> +
> + if (numwritten < 0 && errno == EINVAL) {
> + ksft_print_msg("%s write(%.*s) failed: %s\n", path,
> + (int)(buflen - 1), buf, strerror(errno));
> + return;
> + }
> +
This makes write_file() silently succeed for every EINVAL, not just the
gigantic-hugetlb setup case. Several callers use this helper for writes where
EINVAL is a real test failure, for example drop_caches or split huge page
setup. Those tests can now continue after a failed setup and report misleading
results.
Please keep the common helper strict and ignore EINVAL only in the hugetlb
path that is probing unsupported gigantic page runtime allocation.
> if (numwritten < 0)
> ksft_exit_fail_msg("%s write(%.*s) failed: %s\n", path,
> (int)(buflen - 1),
> buf, strerror(errno));
> --
> 2.52.0
>
>
