Re: [PATCH v3 40/54] selftests/mm: hugetlb-mremap: add setup of HugeTLB pages

Sarthak Sharma
2026-05-05T06:53:01Z

Hi Mike!

On 4/29/26 2:12 AM, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
>
> hugetlb-mremap test fails if there are no free huge pages prepared by a
> wrapper script.
>
> Add setup of HugeTLB pages to the test and make sure that the original
> settings are restored on the test exit.
>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
> tools/testing/selftests/mm/hugetlb-mremap.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/mm/hugetlb-mremap.c b/tools/testing/selftests/mm/hugetlb-mremap.c
> index 1c87c39780c5..09241a279ec2 100644
> --- a/tools/testing/selftests/mm/hugetlb-mremap.c
> +++ b/tools/testing/selftests/mm/hugetlb-mremap.c
> @@ -26,6 +26,7 @@
> #include <stdbool.h>
> #include "kselftest.h"
> #include "vm_util.h"
> +#include "hugepage_settings.h"
>
> #define DEFAULT_LENGTH_MB 10UL
> #define MB_TO_BYTES(x) (x * 1024 * 1024)
> @@ -108,8 +109,9 @@ static void register_region_with_uffd(char *addr, size_t len)
>
> int main(int argc, char *argv[])
> {
> + unsigned long hugepage_size;
> + int ret = 0, fd, nr;
> size_t length = 0;
> - int ret = 0, fd;
>
> ksft_print_header();
> ksft_set_plan(1);
> @@ -125,7 +127,14 @@ int main(int argc, char *argv[])
> else
> length = DEFAULT_LENGTH_MB;
>
> + hugepage_size = default_huge_page_size();
> length = MB_TO_BYTES(length);
> + length = (length + hugepage_size) & ~(hugepage_size - 1);

I might be missing something, but if we're trying to align length to the
hugepage size, should this be:

length = (length + hugepage_size - 1) & ~(hugepage_size - 1);

like in hugetlb-mmap.c? Because the current code will add an extra
hugepage if the length is already aligned.

> + nr = length / hugepage_size;
> +
> + if (!hugetlb_setup_default(nr))
> + ksft_exit_skip("Not enough huge pages\n");
> +
> fd = memfd_create(argv[0], MFD_HUGETLB);
> if (fd < 0)
> ksft_exit_fail_msg("Open failed: %s\n", strerror(errno));