Re: [PATCH 02/11] mm: page_vma_mapped_walk(): settle PageHuge on entry

Peter Xu
2021-06-10T14:17:42Z

On Wed, Jun 09, 2021 at 11:36:36PM -0700, Hugh Dickins wrote:
> page_vma_mapped_walk() cleanup: get the hugetlbfs PageHuge case
> out of the way at the start, so no need to worry about it later.
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Cc: <stable@vger.kernel.org>
> ---
> mm/page_vma_mapped.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index a6dbf714ca15..7c0504641fb8 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -153,10 +153,11 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> if (pvmw->pmd && !pvmw->pte)
> return not_found(pvmw);
>
> - if (pvmw->pte)
> - goto next_pte;
> -
> if (unlikely(PageHuge(page))) {
> + /* The only possible mapping was handled on last iteration */
> + if (pvmw->pte)
> + return not_found(pvmw);
> +
> /* when pud is not present, pte will be NULL */
> pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page));
> if (!pvmw->pte)

Would it be even nicer to move the initial check to be after PageHuge() too?

if (pvmw->pmd && !pvmw->pte)
return not_found(pvmw);

It looks already better, so no strong opinion.

Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks,

--
Peter Xu