linux-kernel - Re: [PATCH 1/3] mm: change vm_get_page_prot() to accept vm_flags

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Message-ID: <1a87887f-7c50-4412-91db-a5b4cf90e6db@arm.com>
Date: Wed, 25 Jun 2025 11:25:01 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Russell King <linux@...linux.org.uk>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
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Subject: Re: [PATCH 1/3] mm: change vm_get_page_prot() to accept vm_flags_t
 argument



On 19/06/25 1:12 AM, Lorenzo Stoakes wrote:
> We abstract the type of the VMA flags to vm_flags_t, however in may places
> it is simply assumed this is unsigned long, which is simply incorrect.
> 
> At the moment this is simply an incongruity, however in future we plan to
> change this type and therefore this change is a critical requirement for
> doing so.
> 
> Overall, this patch does not introduce any functional change.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
>  arch/arm64/mm/mmap.c                       | 2 +-
>  arch/powerpc/include/asm/book3s/64/pkeys.h | 3 ++-
>  arch/sparc/mm/init_64.c                    | 2 +-
>  arch/x86/mm/pgprot.c                       | 2 +-
>  include/linux/mm.h                         | 4 ++--
>  include/linux/pgtable.h                    | 2 +-
>  tools/testing/vma/vma_internal.h           | 2 +-
>  7 files changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
> index c86c348857c4..08ee177432c2 100644
> --- a/arch/arm64/mm/mmap.c
> +++ b/arch/arm64/mm/mmap.c
> @@ -81,7 +81,7 @@ static int __init adjust_protection_map(void)
>  }
>  arch_initcall(adjust_protection_map);
>  
> -pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
>  {
>  	ptdesc_t prot;
>  
> diff --git a/arch/powerpc/include/asm/book3s/64/pkeys.h b/arch/powerpc/include/asm/book3s/64/pkeys.h
> index 5b178139f3c0..6f2075636591 100644
> --- a/arch/powerpc/include/asm/book3s/64/pkeys.h
> +++ b/arch/powerpc/include/asm/book3s/64/pkeys.h
> @@ -4,8 +4,9 @@
>  #define _ASM_POWERPC_BOOK3S_64_PKEYS_H
>  
>  #include <asm/book3s/64/hash-pkey.h>
> +#include <linux/mm_types.h>
>  
> -static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
> +static inline u64 vmflag_to_pte_pkey_bits(vm_flags_t vm_flags)
>  {
>  	if (!mmu_has_feature(MMU_FTR_PKEY))
>  		return 0x0UL;
> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index 25ae4c897aae..7ed58bf3aaca 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -3201,7 +3201,7 @@ void copy_highpage(struct page *to, struct page *from)
>  }
>  EXPORT_SYMBOL(copy_highpage);
>  
> -pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
>  {
>  	unsigned long prot = pgprot_val(protection_map[vm_flags &
>  					(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
> diff --git a/arch/x86/mm/pgprot.c b/arch/x86/mm/pgprot.c
> index c84bd9540b16..dc1afd5c839d 100644
> --- a/arch/x86/mm/pgprot.c
> +++ b/arch/x86/mm/pgprot.c
> @@ -32,7 +32,7 @@ void add_encrypt_protection_map(void)
>  		protection_map[i] = pgprot_encrypted(protection_map[i]);
>  }
>  
> -pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
>  {
>  	unsigned long val = pgprot_val(protection_map[vm_flags &
>  				      (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 98a606908307..7a7cd2e1b2af 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3487,10 +3487,10 @@ static inline bool range_in_vma(struct vm_area_struct *vma,
>  }
>  
>  #ifdef CONFIG_MMU
> -pgprot_t vm_get_page_prot(unsigned long vm_flags);
> +pgprot_t vm_get_page_prot(vm_flags_t vm_flags);
>  void vma_set_page_prot(struct vm_area_struct *vma);
>  #else
> -static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +static inline pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
>  {
>  	return __pgprot(0);
>  }
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 1d4439499503..cf1515c163e2 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -2001,7 +2001,7 @@ typedef unsigned int pgtbl_mod_mask;
>   *								x: (yes) yes
>   */
>  #define DECLARE_VM_GET_PAGE_PROT					\
> -pgprot_t vm_get_page_prot(unsigned long vm_flags)			\
> +pgprot_t vm_get_page_prot(vm_flags_t vm_flags)				\
>  {									\
>  		return protection_map[vm_flags &			\
>  			(VM_READ | VM_WRITE | VM_EXEC | VM_SHARED)];	\
> diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
> index d7fea56e3bb3..4e3a2f1ac09e 100644
> --- a/tools/testing/vma/vma_internal.h
> +++ b/tools/testing/vma/vma_internal.h
> @@ -581,7 +581,7 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
>  	return __pgprot(pgprot_val(oldprot) | pgprot_val(newprot));
>  }
>  
> -static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +static inline pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
>  {
>  	return __pgprot(vm_flags);
>  }

LGTM

Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>