Re: [PATCH V2 4/5] mm/hugetlb: Add prot_modify_start/commit sequence for hugetlb update

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 28 Nov 2018 20:04:37 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> wrote:

> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

Some explanation of the motivation would be useful.

>  include/linux/hugetlb.h | 18 ++++++++++++++++++
>  mm/hugetlb.c            |  8 +++++---
>  2 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 087fd5f48c91..e2a3b0c854eb 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -543,6 +543,24 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr
>  	set_huge_pte_at(mm, addr, ptep, pte);
>  }
>  #endif
> +
> +#ifndef huge_ptep_modify_prot_start
> +static inline pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma,
> +						unsigned long addr, pte_t *ptep)
> +{
> +	return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
> +}
> +#endif

#define huge_ptep_modify_prot_start huge_ptep_modify_prot_start

> +#ifndef huge_ptep_modify_prot_commit
> +static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
> +						unsigned long addr, pte_t *ptep,
> +						pte_t old_pte, pte_t pte)
> +{
> +	set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
> +}
> +#endif

#define huge_ptep_modify_prot_commit huge_ptep_modify_prot_commit