Re: [PATCH v1 5/5] mm: Add update_mmu_tlb_range()

["Bang Li" <libang.li@xxxxxxxxxxxx>]

Hey Lance,

Thanks for taking time to review!

On 2024/4/29 19:23, Lance Yang wrote:
> Hey Bang,
>
> On Mon, Apr 29, 2024 at 6:36 PM Bang Li <libang.li@xxxxxxxxxxxx> wrote:
> > After the commit 19eaf44954df ("mm: thp: support allocation of anonymous
> > multi-size THP"), it may need to batch update tlb of an address range
> > through the update_mmu_tlb function. We can simplify this operation by
> > adding the update_mmu_tlb_range function, which may also reduce the
> > execution of some unnecessary code in some architectures.
> >
> > Signed-off-by: Bang Li <libang.li@xxxxxxxxxxxx>
> > ---
> >   include/linux/pgtable.h | 5 +++++
> >   mm/memory.c             | 4 +---
> >   2 files changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> > index 18019f037bae..73411dfebf7a 100644
> > --- a/include/linux/pgtable.h
> > +++ b/include/linux/pgtable.h
> > @@ -734,6 +734,11 @@ static inline void update_mmu_tlb(struct vm_area_struct *vma,
> >                                  unsigned long address, pte_t *ptep)
> >   {
> >   }
> > +
> > +static inline void update_mmu_tlb_range(struct vm_area_struct *vma,
> > +                               unsigned long address, pte_t *ptep, unsigned int nr)
> > +{
> > +}
> >   #define __HAVE_ARCH_UPDATE_MMU_TLB
> >   #endif
>
> IMO, it might be better to use a separate definition to determine whether
> update_mmu_tlb_range() is overridden by a specific architecture.

I have also considered this, and I will modify it in the next version.
thank you again for your review!

Thanks,
Bang

> Thanks,
> Lance
>
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 6647685fd3c4..1f0ca362b82a 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -4396,7 +4396,6 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
> >          vm_fault_t ret = 0;
> >          int nr_pages = 1;
> >          pte_t entry;
> > -       int i;
> >
> >          /* File mapping without ->vm_ops ? */
> >          if (vma->vm_flags & VM_SHARED)
> > @@ -4465,8 +4464,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
> >                  update_mmu_tlb(vma, addr, vmf->pte);
> >                  goto release;
> >          } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) {
> > -               for (i = 0; i < nr_pages; i++)
> > -                       update_mmu_tlb(vma, addr + PAGE_SIZE * i, vmf->pte + i);
> > +               update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages);
> >                  goto release;
> >          }
> >
> > --
> > 2.19.1.6.gb485710b