Re: [PATCH] selftests: mincore: use default huge page size for hugetlb test

[Andrew Morton]

On Fri, 26 Jun 2026 20:59:02 +0800 "Yijia Wang" <wangyijia.yeah@xxxxxxxxxxxxx> wrote:

> The hugetlb mincore test passes the base page size as the MAP_HUGETLB
> mapping length.  This works on systems where the default huge page size
> is the same as the base page size, but mmap() can fail with EINVAL before
> mincore() is exercised when the default huge page size is larger, such as
> on arm64 systems with 64K base pages and 2M huge pages.
> 
> Use the default huge page size from /proc/meminfo for the hugetlb mapping
> and unmap length.  Keep the mincore() check scoped to one base page since
> the test only needs to verify the residency state before and after the
> mapping is touched.  This also avoids changing the mincore() length to the
> whole huge page, which would require a larger residency vector because
> mincore() reports one byte per base page.

Thanks.

AI review flagged a couple of possible issues - can you please take a
look?

https://sashiko.dev/#/patchset/20260626-b4-mincore-preview-v1-1-5f07aa02ab32@xxxxxxxxxxxxx

> --- a/tools/testing/selftests/mincore/mincore_selftest.c
> +++ b/tools/testing/selftests/mincore/mincore_selftest.c
> @@ -22,6 +22,27 @@
>  #define MB (1UL << 20)
>  #define FILE_SIZE (4 * MB)
>  
> +static unsigned long default_huge_page_size(void)

This would be our fifth(?) implementation of default_huge_page_size()
in tools/testing/selftests.  There's a project for someone!