On Fri, May 10, 2024 at 5:05 PM Ryan Roberts <ryan.roberts@xxxxxxx> wrote:
>
> On 06/05/2024 16:51, Bang Li 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 | 8 ++++++++
> > mm/memory.c | 4 +---
> > 2 files changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> > index 18019f037bae..869bfe6054f1 100644
> > --- a/include/linux/pgtable.h
> > +++ b/include/linux/pgtable.h
> > @@ -737,6 +737,14 @@ static inline void update_mmu_tlb(struct vm_area_struct *vma,
> > #define __HAVE_ARCH_UPDATE_MMU_TLB
> > #endif
>
> Given you are implementing update_mmu_tlb_range() in all the arches that
> currently override update_mmu_tlb() I wonder if it would be cleaner to remove
> update_mmu_tlb() from all those arches, and define generically, removing the
> ability for arches to override it:
Sounds great! Let's get it done.
>
> static inline void update_mmu_tlb(struct vm_area_struct *vma,
> unsigned long address, pte_t *ptep)
> {
> update_mmu_tlb_range(vma, address, ptep, 1);
> }
>
> >
> > +#ifndef __HAVE_ARCH_UPDATE_MMU_TLB_RANGE
> > +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_RANGE
> > +#endif
>
> Then you could use the modern override scheme as Lance suggested and you won't
> have any confusion with __HAVE_ARCH_UPDATE_MMU_TLB because it won't exist anymore.
+1. It might be better to use the modern override scheme :)
Thanks,
Lance
>
> > +
> > /*
> > * Some architectures may be able to avoid expensive synchronization
> > * primitives when modifications are made to PTE's which are already
> > diff --git a/mm/memory.c b/mm/memory.c
> > index eea6e4984eae..2d53e29cf76e 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -4421,7 +4421,6 @@ 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)
> > @@ -4491,8 +4490,7 @@ 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);
>
> I certainly agree that this will be a useful helper to have. I expect there will
> be more users in future.
>
> > goto release;
> > }
> >
>
