Re: [PATCH v1 2/3] selftests/mm: uffd-unit-tests support for hugepages > 2M

[Rafael Aquini <raquini@redhat.com>]

On Tue, Mar 18, 2025 at 05:43:40PM +0000, Ryan Roberts wrote:
> uffd-unit-tests uses a memory area with a fixed 32M size. Then it
> calculates the number of pages by dividing by page_size, which itself is
> either the base page size or the PMD huge page size depending on the
> test config. For the latter, we end up with nr_pages=1 for arm64 16K
> base pages, and nr_pages=0 for 64K base pages. This doesn't end well.
> 
> So let's make the 32M size a floor and also ensure that we have at least
> 2 pages given the PMD size. With this change, the tests pass on arm64
> 64K base page size configuration.
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
>  tools/testing/selftests/mm/uffd-unit-tests.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
> index 74c8bc02b506..6973e57b227a 100644
> --- a/tools/testing/selftests/mm/uffd-unit-tests.c
> +++ b/tools/testing/selftests/mm/uffd-unit-tests.c
> @@ -26,6 +26,8 @@
>  #define ALIGN_UP(x, align_to) \
>  	((__typeof__(x))((((unsigned long)(x)) + ((align_to)-1)) & ~((align_to)-1)))
>  
> +#define MAX(a, b) (((a) > (b)) ? (a) : (b))
> +
>  struct mem_type {
>  	const char *name;
>  	unsigned int mem_flag;
> @@ -196,7 +198,8 @@ uffd_setup_environment(uffd_test_args_t *args, uffd_test_case_t *test,
>  	else
>  		page_size = psize();
>  
> -	nr_pages = UFFD_TEST_MEM_SIZE / page_size;
> +	/* Ensure we have at least 2 pages */
> +	nr_pages = MAX(UFFD_TEST_MEM_SIZE, page_size * 2) / page_size;
>  	/* TODO: remove this global var.. it's so ugly */
>  	nr_cpus = 1;
>  
> -- 
> 2.43.0
> 
 
Acked-by: Rafael Aquini <raquini@redhat.com>