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:
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.
> +
> /*
> * 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;
> }
>
