On Tue, Jun 17, 2025 at 05:43:37PM +0200, David Hildenbrand wrote:
> Just like we do for vmf_insert_page_mkwrite() -> ... ->
> insert_page_into_pte_locked(), support the huge zero folio.
>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
insert_page_into_pte_locked() creates a special pte in case it finds the
zero folio while insert_pmd() doesn't.
I know that we didn't want to create special mappings for normal refcount folios
but this seems inconsistent? I'm pretty sure there's a reason but could you
elaborate on that?
> ---
> mm/huge_memory.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1ea23900b5adb..92400f3baa9ff 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1418,9 +1418,11 @@ static vm_fault_t insert_pmd(struct vm_area_struct *vma, unsigned long addr,
> if (fop.is_folio) {
> entry = folio_mk_pmd(fop.folio, vma->vm_page_prot);
>
> - folio_get(fop.folio);
> - folio_add_file_rmap_pmd(fop.folio, &fop.folio->page, vma);
> - add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR);
> + if (!is_huge_zero_folio(fop.folio)) {
> + folio_get(fop.folio);
> + folio_add_file_rmap_pmd(fop.folio, &fop.folio->page, vma);
> + add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR);
> + }
> } else {
> entry = pmd_mkhuge(pfn_pmd(fop.pfn, prot));
> entry = pmd_mkspecial(entry);
> --
> 2.49.0
>
>
--
Oscar Salvador
SUSE Labs
