linux-kernel - Re: [PATCH v2 15/46] hugetlb: add make_huge_pte_with

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Date:   Wed, 22 Feb 2023 14:53:42 -0800
From:   James Houghton <jthoughton@...gle.com>
To:     Mina Almasry <almasrymina@...gle.com>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Peter Xu <peterx@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        "Zach O'Keefe" <zokeefe@...gle.com>,
        Manish Mishra <manish.mishra@...anix.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Yang Shi <shy828301@...il.com>,
        Frank van der Linden <fvdl@...gle.com>,
        Jiaqi Yan <jiaqiyan@...gle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 15/46] hugetlb: add make_huge_pte_with_shift

On Wed, Feb 22, 2023 at 1:15 PM Mina Almasry <almasrymina@...gle.com> wrote:
>
> On Fri, Feb 17, 2023 at 4:28 PM James Houghton <jthoughton@...gle.com> wrote:
> >
> > This allows us to make huge PTEs at shifts other than the hstate shift,
> > which will be necessary for high-granularity mappings.
> >
> > Acked-by: Mike Kravetz <mike.kravetz@...cle.com>
> > Signed-off-by: James Houghton <jthoughton@...gle.com>
> >
>
> Reviewed-by: Mina Almasry <almasrymina@...gle.com>

Thank you :)

>
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index f74183acc521..ed1d806020de 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -5110,11 +5110,11 @@ const struct vm_operations_struct hugetlb_vm_ops = {
> >         .pagesize = hugetlb_vm_op_pagesize,
> >  };
> >
> > -static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
> > -                               int writable)
> > +static pte_t make_huge_pte_with_shift(struct vm_area_struct *vma,
> > +                                     struct page *page, int writable,
> > +                                     int shift)
>
> Nit: can this be 'unsigned int shift'. Because you're actually passing
> it an unsigned int below and there is an implicit cast there. Yes it
> will never matter, I know...

Yes I think it should be unsigned int. Thanks for the catch.

>
> >  {
> >         pte_t entry;
> > -       unsigned int shift = huge_page_shift(hstate_vma(vma));
> >
> >         if (writable) {
> >                 entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_pte(page,
> > @@ -5128,6 +5128,14 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
> >         return entry;
> >  }
> >
> > +static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
> > +                          int writable)
> > +{
> > +       unsigned int shift = huge_page_shift(hstate_vma(vma));
> > +
> > +       return make_huge_pte_with_shift(vma, page, writable, shift);
> > +}
> > +
> >  static void set_huge_ptep_writable(struct vm_area_struct *vma,
> >                                    unsigned long address, pte_t *ptep)
> >  {
> > --
> > 2.39.2.637.g21b0678d19-goog
> >