Re: [PATCH 1/2] mm/page_vma_mapped: use PMD_SIZE instead of calculating it

Kirill A. Shutemov
2019-11-28T08:33:00Z

On Thu, Nov 28, 2019 at 09:03:20AM +0800, Wei Yang wrote:
> At this point, we are sure page is PageTransHuge, which means
> hpage_nr_pages is HPAGE_PMD_NR.
>
> This is safe to use PMD_SIZE instead of calculating it.
>
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
> ---
> mm/page_vma_mapped.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index eff4b4520c8d..76e03650a3ab 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -223,7 +223,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> if (pvmw->address >= pvmw->vma->vm_end ||
> pvmw->address >=
> __vma_address(pvmw->page, pvmw->vma) +
> - hpage_nr_pages(pvmw->page) * PAGE_SIZE)
> + PMD_SIZE)
> return not_found(pvmw);
> /* Did we cross page table boundary? */
> if (pvmw->address % PMD_SIZE == 0) {

It is dubious cleanup. Maybe page_size(pvmw->page) instead? It will not
break if we ever get PUD THP pages.

--
Kirill A. Shutemov