Subject: Re: [PATCH] mm: Merge pte_mkhuge() call into arch_make_huge_pte()

From: Mike Rapoport <[email-masked]>
Date: Wed, 2 Feb 2022 08:18:21 +0200

On Wed, Feb 02, 2022 at 11:08:06AM +0530, Anshuman Khandual wrote:
> Each call into pte_mkhuge() is invariably followed by arch_make_huge_pte().
> Instead arch_make_huge_pte() can accommodate pte_mkhuge() at the beginning.
> This updates generic fallback stub for arch_make_huge_pte() and available
> platforms definitions. This makes huge pte creation much cleaner and easier
> to follow.

Won't it break architectures that don't define arch_make_huge_pte()?
 
> Cc: Catalin Marinas <[email-masked]>
> Cc: Will Deacon <[email-masked]>
> Cc: Michael Ellerman <[email-masked]>
> Cc: Paul Mackerras <[email-masked]>
> Cc: "David S. Miller" <[email-masked]>
> Cc: Mike Kravetz <[email-masked]>
> Cc: Andrew Morton <[email-masked]>
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Cc: [email-masked]
> Signed-off-by: Anshuman Khandual <[email-masked]>
> ---
>  arch/arm64/mm/hugetlbpage.c                      | 1 +
>  arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h | 1 +
>  arch/sparc/mm/hugetlbpage.c                      | 1 +
>  include/linux/hugetlb.h                          | 2 +-
>  mm/hugetlb.c                                     | 3 +--
>  mm/vmalloc.c                                     | 1 -
>  6 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index ffb9c229610a..228226c5fa80 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -347,6 +347,7 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
>  {
>  	size_t pagesize = 1UL << shift;
>  
> +	entry = pte_mkhuge(entry);
>  	if (pagesize == CONT_PTE_SIZE) {
>  		entry = pte_mkcont(entry);
>  	} else if (pagesize == CONT_PMD_SIZE) {
> diff --git a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
> index 64b6c608eca4..e41e095158c7 100644
> --- a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
> +++ b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
> @@ -70,6 +70,7 @@ static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags
>  {
>  	size_t size = 1UL << shift;
>  
> +	entry = pte_mkhuge(entry);
>  	if (size == SZ_16K)
>  		return __pte(pte_val(entry) & ~_PAGE_HUGE);
>  	else
> diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
> index 0f49fada2093..d8e0e3c7038d 100644
> --- a/arch/sparc/mm/hugetlbpage.c
> +++ b/arch/sparc/mm/hugetlbpage.c
> @@ -181,6 +181,7 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
>  {
>  	pte_t pte;
>  
> +	entry = pte_mkhuge(entry);
>  	pte = hugepage_shift_to_tte(entry, shift);
>  
>  #ifdef CONFIG_SPARC64
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index d1897a69c540..52c462390aee 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -754,7 +754,7 @@ static inline void arch_clear_hugepage_flags(struct page *page) { }
>  static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift,
>  				       vm_flags_t flags)
>  {
> -	return entry;
> +	return pte_mkhuge(entry);
>  }
>  #endif
>  
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 61895cc01d09..5ca253c1b4e4 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -4637,7 +4637,6 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
>  					   vma->vm_page_prot));
>  	}
>  	entry = pte_mkyoung(entry);
> -	entry = pte_mkhuge(entry);
>  	entry = arch_make_huge_pte(entry, shift, vma->vm_flags);
>  
>  	return entry;
> @@ -6172,7 +6171,7 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
>  			unsigned int shift = huge_page_shift(hstate_vma(vma));
>  
>  			old_pte = huge_ptep_modify_prot_start(vma, address, ptep);
> -			pte = pte_mkhuge(huge_pte_modify(old_pte, newprot));
> +			pte = huge_pte_modify(old_pte, newprot);
>  			pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
>  			huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
>  			pages++;
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 4165304d3547..d0b14dd73adc 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -118,7 +118,6 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>  		if (size != PAGE_SIZE) {
>  			pte_t entry = pfn_pte(pfn, prot);
>  
> -			entry = pte_mkhuge(entry);
>  			entry = arch_make_huge_pte(entry, ilog2(size), 0);
>  			set_huge_pte_at(&init_mm, addr, pte, entry);
>  			pfn += PFN_DOWN(size);
> -- 
> 2.25.1
> 
> 

-- 
Sincerely yours,
Mike.