linux-kernel - Re: [PATCH 01/12] mm, arm64: Rename ARM64_CONTPTE to THP

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Message-ID: <CAGsJ_4xayC4D4y0d7SPXxCvuW4-rJQUCa_-OUDSsOGm_HyPm1w@mail.gmail.com>
Date: Thu, 9 May 2024 12:46:35 +1200
From: Barry Song <21cnbao@...il.com>
To: Alexandre Ghiti <alexghiti@...osinc.com>
Cc: Ryan Roberts <ryan.roberts@....com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Alexander Potapenko <glider@...gle.com>, Marco Elver <elver@...gle.com>, 
	Dmitry Vyukov <dvyukov@...gle.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Ard Biesheuvel <ardb@...nel.org>, Anup Patel <anup@...infault.org>, 
	Atish Patra <atishp@...shpatra.org>, Andrey Ryabinin <ryabinin.a.a@...il.com>, 
	Andrey Konovalov <andreyknvl@...il.com>, Vincenzo Frascino <vincenzo.frascino@....com>, 
	Andrew Morton <akpm@...ux-foundation.org>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com, 
	linux-riscv@...ts.infradead.org, linux-efi@...r.kernel.org, 
	kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, linux-mm@...ck.org
Subject: Re: [PATCH 01/12] mm, arm64: Rename ARM64_CONTPTE to THP_CONTPTE

On Thu, May 9, 2024 at 7:20 AM Alexandre Ghiti <alexghiti@...osinc.com> wrote:
>
> The ARM64_CONTPTE config represents the capability to transparently use
> contpte mappings for THP userspace mappings, which will be implemented
> in the next commits for riscv, so make this config more generic and move
> it to mm.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
> ---
>  arch/arm64/Kconfig               | 9 ---------
>  arch/arm64/include/asm/pgtable.h | 6 +++---
>  arch/arm64/mm/Makefile           | 2 +-
>  mm/Kconfig                       | 9 +++++++++
>  4 files changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index ac2f6d906cc3..9d823015b4e5 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -2227,15 +2227,6 @@ config UNWIND_PATCH_PAC_INTO_SCS
>         select UNWIND_TABLES
>         select DYNAMIC_SCS
>
> -config ARM64_CONTPTE
> -       bool "Contiguous PTE mappings for user memory" if EXPERT
> -       depends on TRANSPARENT_HUGEPAGE
> -       default y
> -       help
> -         When enabled, user mappings are configured using the PTE contiguous
> -         bit, for any mappings that meet the size and alignment requirements.
> -         This reduces TLB pressure and improves performance.
> -
>  endmenu # "Kernel Features"
>
>  menu "Boot options"
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 7c2938cb70b9..1758ce71fae9 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -1369,7 +1369,7 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
>                                     unsigned long addr, pte_t *ptep,
>                                     pte_t old_pte, pte_t new_pte);
>
> -#ifdef CONFIG_ARM64_CONTPTE
> +#ifdef CONFIG_THP_CONTPTE

Is it necessarily THP? can't be hugetlb or others? I feel THP_CONTPTE
isn't a good name.

>
>  /*
>   * The contpte APIs are used to transparently manage the contiguous bit in ptes
> @@ -1622,7 +1622,7 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
>         return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirty);
>  }
>
> -#else /* CONFIG_ARM64_CONTPTE */
> +#else /* CONFIG_THP_CONTPTE */
>
>  #define ptep_get                               __ptep_get
>  #define set_pte                                        __set_pte
> @@ -1642,7 +1642,7 @@ static inline int ptep_set_access_flags(struct vm_area_struct *vma,
>  #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
>  #define ptep_set_access_flags                  __ptep_set_access_flags
>
> -#endif /* CONFIG_ARM64_CONTPTE */
> +#endif /* CONFIG_THP_CONTPTE */
>
>  int find_num_contig(struct mm_struct *mm, unsigned long addr,
>                     pte_t *ptep, size_t *pgsize);
> diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
> index 60454256945b..52a1b2082627 100644
> --- a/arch/arm64/mm/Makefile
> +++ b/arch/arm64/mm/Makefile
> @@ -3,7 +3,7 @@ obj-y                           := dma-mapping.o extable.o fault.o init.o \
>                                    cache.o copypage.o flush.o \
>                                    ioremap.o mmap.o pgd.o mmu.o \
>                                    context.o proc.o pageattr.o fixmap.o
> -obj-$(CONFIG_ARM64_CONTPTE)    += contpte.o
> +obj-$(CONFIG_THP_CONTPTE)      += contpte.o
>  obj-$(CONFIG_HUGETLB_PAGE)     += hugetlbpage.o
>  obj-$(CONFIG_PTDUMP_CORE)      += ptdump.o
>  obj-$(CONFIG_PTDUMP_DEBUGFS)   += ptdump_debugfs.o
> diff --git a/mm/Kconfig b/mm/Kconfig
> index c325003d6552..fd4de221a1c6 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -984,6 +984,15 @@ config ARCH_HAS_CACHE_LINE_SIZE
>  config ARCH_HAS_CONTPTE
>         bool
>
> +config THP_CONTPTE
> +       bool "Contiguous PTE mappings for user memory" if EXPERT
> +       depends on ARCH_HAS_CONTPTE && TRANSPARENT_HUGEPAGE
> +       default y
> +       help
> +         When enabled, user mappings are configured using the PTE contiguous
> +         bit, for any mappings that meet the size and alignment requirements.
> +         This reduces TLB pressure and improves performance.
> +
>  config ARCH_HAS_CURRENT_STACK_POINTER
>         bool
>         help
> --
> 2.39.2

Thanks
Barry