mm: Remove unnecessary __GFP_HIGHMEM in __p*d_alloc_one_*()

[PATCH V2] mm: Remove unnecessary __GFP_HIGHMEM in __p*d_alloc_one_*()

Posted by Huacai Chen 1 month, 1 week ago

__{pgd,p4d,pud,pmd,pte}_alloc_one_*() always allocate pages with GFP
flag GFP_PGTABLE_KERNEL/GFP_PGTABLE_USER. These two macros are defined
as follows:

 #define GFP_PGTABLE_KERNEL	(GFP_KERNEL | __GFP_ZERO)
 #define GFP_PGTABLE_USER	(GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)

There is no __GFP_HIGHMEM in them, so we needn't to clear __GFP_HIGHMEM
explicitly.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
V2: Change the subject line as Vishal suggested.

 include/asm-generic/pgalloc.h | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 3c8ec3bfea44..706e87b43b19 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -18,8 +18,7 @@
  */
 static inline pte_t *__pte_alloc_one_kernel_noprof(struct mm_struct *mm)
 {
-	struct ptdesc *ptdesc = pagetable_alloc_noprof(GFP_PGTABLE_KERNEL &
-			~__GFP_HIGHMEM, 0);
+	struct ptdesc *ptdesc = pagetable_alloc_noprof(GFP_PGTABLE_KERNEL, 0);
 
 	if (!ptdesc)
 		return NULL;
@@ -172,7 +171,6 @@ static inline pud_t *__pud_alloc_one_noprof(struct mm_struct *mm, unsigned long
 
 	if (mm == &init_mm)
 		gfp = GFP_PGTABLE_KERNEL;
-	gfp &= ~__GFP_HIGHMEM;
 
 	ptdesc = pagetable_alloc_noprof(gfp, 0);
 	if (!ptdesc)
@@ -226,7 +224,6 @@ static inline p4d_t *__p4d_alloc_one_noprof(struct mm_struct *mm, unsigned long
 
 	if (mm == &init_mm)
 		gfp = GFP_PGTABLE_KERNEL;
-	gfp &= ~__GFP_HIGHMEM;
 
 	ptdesc = pagetable_alloc_noprof(gfp, 0);
 	if (!ptdesc)
@@ -270,7 +267,6 @@ static inline pgd_t *__pgd_alloc_noprof(struct mm_struct *mm, unsigned int order
 
 	if (mm == &init_mm)
 		gfp = GFP_PGTABLE_KERNEL;
-	gfp &= ~__GFP_HIGHMEM;
 
 	ptdesc = pagetable_alloc_noprof(gfp, order);
 	if (!ptdesc)
-- 
2.47.3

Re: [PATCH V2] mm: Remove unnecessary __GFP_HIGHMEM in __p*d_alloc_one_*()

Posted by Kevin Brodsky 1 month, 1 week ago

On 09/11/2025 02:18, Huacai Chen wrote:
> __{pgd,p4d,pud,pmd,pte}_alloc_one_*() always allocate pages with GFP
> flag GFP_PGTABLE_KERNEL/GFP_PGTABLE_USER. These two macros are defined
> as follows:
>
>  #define GFP_PGTABLE_KERNEL	(GFP_KERNEL | __GFP_ZERO)
>  #define GFP_PGTABLE_USER	(GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
>
> There is no __GFP_HIGHMEM in them, so we needn't to clear __GFP_HIGHMEM

Nit: "needn't clear" (or simply "don't need to")

> explicitly.
>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>

- Kevin

Re: [PATCH V2] mm: Remove unnecessary __GFP_HIGHMEM in __p*d_alloc_one_*()

Posted by Anshuman Khandual 1 month, 1 week ago

On 09/11/25 7:48 AM, Huacai Chen wrote:
> __{pgd,p4d,pud,pmd,pte}_alloc_one_*() always allocate pages with GFP
> flag GFP_PGTABLE_KERNEL/GFP_PGTABLE_USER. These two macros are defined
> as follows:
> 
>  #define GFP_PGTABLE_KERNEL	(GFP_KERNEL | __GFP_ZERO)
>  #define GFP_PGTABLE_USER	(GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
> 
> There is no __GFP_HIGHMEM in them, so we needn't to clear __GFP_HIGHMEM
> explicitly.
> 
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
> V2: Change the subject line as Vishal suggested.
> 
>  include/asm-generic/pgalloc.h | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
> index 3c8ec3bfea44..706e87b43b19 100644
> --- a/include/asm-generic/pgalloc.h
> +++ b/include/asm-generic/pgalloc.h
> @@ -18,8 +18,7 @@
>   */
>  static inline pte_t *__pte_alloc_one_kernel_noprof(struct mm_struct *mm)
>  {
> -	struct ptdesc *ptdesc = pagetable_alloc_noprof(GFP_PGTABLE_KERNEL &
> -			~__GFP_HIGHMEM, 0);
> +	struct ptdesc *ptdesc = pagetable_alloc_noprof(GFP_PGTABLE_KERNEL, 0);
>  
>  	if (!ptdesc)
>  		return NULL;
> @@ -172,7 +171,6 @@ static inline pud_t *__pud_alloc_one_noprof(struct mm_struct *mm, unsigned long
>  
>  	if (mm == &init_mm)
>  		gfp = GFP_PGTABLE_KERNEL;
> -	gfp &= ~__GFP_HIGHMEM;
>  
>  	ptdesc = pagetable_alloc_noprof(gfp, 0);
>  	if (!ptdesc)
> @@ -226,7 +224,6 @@ static inline p4d_t *__p4d_alloc_one_noprof(struct mm_struct *mm, unsigned long
>  
>  	if (mm == &init_mm)
>  		gfp = GFP_PGTABLE_KERNEL;
> -	gfp &= ~__GFP_HIGHMEM;
>  
>  	ptdesc = pagetable_alloc_noprof(gfp, 0);
>  	if (!ptdesc)
> @@ -270,7 +267,6 @@ static inline pgd_t *__pgd_alloc_noprof(struct mm_struct *mm, unsigned int order
>  
>  	if (mm == &init_mm)
>  		gfp = GFP_PGTABLE_KERNEL;
> -	gfp &= ~__GFP_HIGHMEM;
>  
>  	ptdesc = pagetable_alloc_noprof(gfp, order);
>  	if (!ptdesc)

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

Re: [PATCH V2] mm: Remove unnecessary __GFP_HIGHMEM in __p*d_alloc_one_*()

Posted by Vishal Moola (Oracle) 1 month, 1 week ago

On Sun, Nov 09, 2025 at 10:18:17AM +0800, Huacai Chen wrote:
> __{pgd,p4d,pud,pmd,pte}_alloc_one_*() always allocate pages with GFP
> flag GFP_PGTABLE_KERNEL/GFP_PGTABLE_USER. These two macros are defined
> as follows:
> 
>  #define GFP_PGTABLE_KERNEL	(GFP_KERNEL | __GFP_ZERO)
>  #define GFP_PGTABLE_USER	(GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
> 
> There is no __GFP_HIGHMEM in them, so we needn't to clear __GFP_HIGHMEM
> explicitly.
> 
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>