[PATCH v6 03/33] pgtable: Create struct ptdesc

Vishal Moola vishal.moola at gmail.com
Tue Jun 27 10:51:59 PDT 2023


On Tue, Jun 27, 2023 at 9:07 AM Peter Xu <peterx at redhat.com> wrote:
>
> On Mon, Jun 26, 2023 at 08:14:01PM -0700, Vishal Moola (Oracle) wrote:
> > Currently, page table information is stored within struct page. As part
> > of simplifying struct page, create struct ptdesc for page table
> > information.
> >
> > Signed-off-by: Vishal Moola (Oracle) <vishal.moola at gmail.com>
> > Acked-by: Mike Rapoport (IBM) <rppt at kernel.org>
> > ---
> >  include/linux/pgtable.h | 68 +++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 68 insertions(+)
> >
> > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> > index 5063b482e34f..d46cb709ce08 100644
> > --- a/include/linux/pgtable.h
> > +++ b/include/linux/pgtable.h
> > @@ -987,6 +987,74 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma,
> >  #endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
> >  #endif /* CONFIG_MMU */
> >
> > +
> > +/**
> > + * struct ptdesc -    Memory descriptor for page tables.
> > + * @__page_flags:     Same as page flags. Unused for page tables.
> > + * @pt_rcu_head:      For freeing page table pages.
> > + * @pt_list:          List of used page tables. Used for s390 and x86.
> > + * @_pt_pad_1:        Padding that aliases with page's compound head.
> > + * @pmd_huge_pte:     Protected by ptdesc->ptl, used for THPs.
> > + * @_pt_s390_gaddr:   Aliases with page's mapping. Used for s390 gmap only.
>
> Should some arch-specific bits (and a few others) always under some
> #ifdefs, so it shouldn't appear on other archs?

Right now this struct completely overlays struct page, so the padding as
well as any arch-specific fields have to stay. Whenever we get ptdescs
independent of struct page we can cleanup any unnecessary fields, as
well as omit unnecessary fields from unrelated architectures.



More information about the linux-riscv mailing list