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    SubjectRe: [PATCH 02/11] mm: page_vma_mapped_walk(): settle PageHuge on entry
    On Thu, 10 Jun 2021, Peter Xu wrote:
    > 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.

    It hadn't occurred to me to move that. I probably wanted those two
    "The only possible mapping" comments near each other. I don't see any
    particular reason to change them around now - beyond the title saying
    "settle PageHuge on entry", whereas this is a few lines after entry!

    Let's leave it as is.

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

    Thanks,
    Hugh

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