Re: [PATCH v4 3/5] selftests/mm: reimplement is_backed_by_thp() with more precise check

On Thu, Aug 14, 2025 at 10:39:12PM -0400, Zi Yan wrote:

and rename it to is_backed_by_folio().

is_backed_by_folio() checks if the given vaddr is backed a folio with a given order. It does so by:

1. getting the pfn of the vaddr;
2. checking kpageflags of the pfn;

if order is greater than 0: 3. checking kpageflags of the head pfn; 4. checking kpageflags of all tail pfns.

pmd_order is added to split_huge_page_test.c and replaces max_order.

Signed-off-by: Zi Yan ziy@nvidia.com

Reviewed-by: Wei Yang richard.weiyang@gmail.com