Re: [PATCH v4 08/15] selftest/mm: align memory size to huge page size in hugepage-mremap test

Zi Yan
2026-04-07T14:57:12Z

On 6 Apr 2026, at 5:19, Sayali Patil wrote:

> The hugepage-mremap selftest uses a default mapping size of 10MB
> when no argument is provided. This size is not guaranteed to be
> aligned to the system hugepage size, which can cause munmap() to fail
> and mremap() to succeed where a failure is expected.
>
> Align the mapping length to the runtime hugepage size using
> default_huge_page_size() to ensure the mapping is properly
> aligned. Also handle the case where
> default_huge_page_size() returns 0 by skipping the test.
>
> Before patch:
> running ./hugepage-mremap
> ------------------------------
> TAP version 13
> 1..1
> Map haddr: Returned address is 0x7eaa40000000
> Map daddr: Returned address is 0x7daa40000000
> Map vaddr: Returned address is 0x7faa40000000
> Address returned by mmap() = 0x7fffaa600000
> Mremap: Returned address is 0x7faa40000000
> First hex is 0
> First hex is 3020100
> Bail out! mremap: Expected failure, but call succeeded
> Planned tests != run tests (1 != 0)
> Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
> [FAIL]
> not ok 1 hugepage-mremap # exit=1
>
> After patch:
> running ./hugepage-mremap
> -------------------------
> TAP version 13
> 1..1
> Map haddr: Returned address is 0x7eaa40000000
> Map daddr: Returned address is 0x7daa40000000
> Map vaddr: Returned address is 0x7faa40000000
> Address returned by mmap() = 0x7fff13000000
> Mremap: Returned address is 0x7faa40000000
> First hex is 0
> First hex is 3020100
> ok 1 Read same data
> Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> [PASS]
> ok 1 hugepage-mremap
>
> Fixes: f77a286de48c ("mm, hugepages: make memory size variable in hugepage-mremap selftest")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
> tools/testing/selftests/mm/hugepage-mremap.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
> index b8f7d92e5a35..f66e4d806477 100644
> --- a/tools/testing/selftests/mm/hugepage-mremap.c
> +++ b/tools/testing/selftests/mm/hugepage-mremap.c
> @@ -32,6 +32,7 @@
>
> #define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
> #define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
> +#define ALIGN(x, a) (((x) + ((a) - 1)) & ~((a) - 1))
>
> static void check_bytes(char *addr)
> {
> @@ -110,6 +111,7 @@ int main(int argc, char *argv[])
> {
> size_t length = 0;
> int ret = 0, fd;
> + size_t hpage_size;
>
> ksft_print_header();
> ksft_set_plan(1);
> @@ -126,6 +128,14 @@ int main(int argc, char *argv[])
> length = DEFAULT_LENGTH_MB;
>
> length = MB_TO_BYTES(length);
> +
> + hpage_size = default_huge_page_size();
> + if (!hpage_size)
> + ksft_exit_skip("Unable to determine huge page size\n");
> +
> + /* Ensure length is hugepage aligned */
> + length = ALIGN(length, hpage_size);
> +
> fd = memfd_create(argv[0], MFD_HUGETLB);
> if (fd < 0)
> ksft_exit_fail_msg("Open failed: %s\n", strerror(errno));
> --
> 2.52.0

LGTM. BTW, it seems that multiple files, pkey-helpers.h, migration.c,
uffed-unit-test.c, hmm-tests.c, have their own ALIGN or ALIGN_UP.
They can be moved to vm_utils.h, later if someone wants to do a cleanup.

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi