Re: [PATCH v3 1/3] mm: hugetlb: Add huge page size param to huge_ptep_get_and_clear()

[Alexander Gordeev <agordeev@linux.ibm.com>]

On Wed, Feb 26, 2025 at 12:06:51PM +0000, Ryan Roberts wrote:
> In order to fix a bug, arm64 needs to be told the size of the huge page
> for which the huge_pte is being cleared in huge_ptep_get_and_clear().
> Provide for this by adding an `unsigned long sz` parameter to the
> function. This follows the same pattern as huge_pte_clear() and
> set_huge_pte_at().
> 
> This commit makes the required interface modifications to the core mm as
> well as all arches that implement this function (arm64, loongarch, mips,
> parisc, powerpc, riscv, s390, sparc). The actual arm64 bug will be fixed
> in a separate commit.
> 
> Cc: stable@vger.kernel.org
> Fixes: 66b3923a1a0f ("arm64: hugetlb: add support for PTE contiguous bit")
> Acked-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> # riscv
> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
>  arch/arm64/include/asm/hugetlb.h     |  4 ++--
>  arch/arm64/mm/hugetlbpage.c          |  8 +++++---
>  arch/loongarch/include/asm/hugetlb.h |  6 ++++--
>  arch/mips/include/asm/hugetlb.h      |  6 ++++--
>  arch/parisc/include/asm/hugetlb.h    |  2 +-
>  arch/parisc/mm/hugetlbpage.c         |  2 +-
>  arch/powerpc/include/asm/hugetlb.h   |  6 ++++--
>  arch/riscv/include/asm/hugetlb.h     |  3 ++-
>  arch/riscv/mm/hugetlbpage.c          |  2 +-
>  arch/s390/include/asm/hugetlb.h      | 16 ++++++++++++----
>  arch/s390/mm/hugetlbpage.c           |  4 ++--
>  arch/sparc/include/asm/hugetlb.h     |  2 +-
>  arch/sparc/mm/hugetlbpage.c          |  2 +-
>  include/asm-generic/hugetlb.h        |  2 +-
>  include/linux/hugetlb.h              |  4 +++-
>  mm/hugetlb.c                         |  4 ++--
>  16 files changed, 46 insertions(+), 27 deletions(-)
...
> diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
> index 7c52acaf9f82..663e87220e89 100644
> --- a/arch/s390/include/asm/hugetlb.h
> +++ b/arch/s390/include/asm/hugetlb.h
> @@ -25,8 +25,16 @@ void __set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
>  #define __HAVE_ARCH_HUGE_PTEP_GET
>  pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
>  
> +pte_t __huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
> +				pte_t *ptep);
> +
>  #define __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
> -pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
> +static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
> +					    unsigned long addr, pte_t *ptep,
> +					    unsigned long sz)
> +{
> +	return __huge_ptep_get_and_clear(mm, addr, ptep);
> +}
>  
>  static inline void arch_clear_hugetlb_flags(struct folio *folio)
>  {
> @@ -48,7 +56,7 @@ static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
>  static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
>  					  unsigned long address, pte_t *ptep)
>  {
> -	return huge_ptep_get_and_clear(vma->vm_mm, address, ptep);
> +	return __huge_ptep_get_and_clear(vma->vm_mm, address, ptep);
>  }
>  
>  #define  __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS
> @@ -59,7 +67,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
>  	int changed = !pte_same(huge_ptep_get(vma->vm_mm, addr, ptep), pte);
>  
>  	if (changed) {
> -		huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
> +		__huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
>  		__set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
>  	}
>  	return changed;
> @@ -69,7 +77,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
>  static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
>  					   unsigned long addr, pte_t *ptep)
>  {
> -	pte_t pte = huge_ptep_get_and_clear(mm, addr, ptep);
> +	pte_t pte = __huge_ptep_get_and_clear(mm, addr, ptep);
>  
>  	__set_huge_pte_at(mm, addr, ptep, pte_wrprotect(pte));
>  }
> diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
> index d9ce199953de..2e568f175cd4 100644
> --- a/arch/s390/mm/hugetlbpage.c
> +++ b/arch/s390/mm/hugetlbpage.c
> @@ -188,8 +188,8 @@ pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
>  	return __rste_to_pte(pte_val(*ptep));
>  }
>  
> -pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
> -			      unsigned long addr, pte_t *ptep)
> +pte_t __huge_ptep_get_and_clear(struct mm_struct *mm,
> +				unsigned long addr, pte_t *ptep)
>  {
>  	pte_t pte = huge_ptep_get(mm, addr, ptep);
>  	pmd_t *pmdp = (pmd_t *) ptep;
...

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390

Thanks!