Re: [RFC PATCH 3/3] mm/hugetlb: Remove pmd_huge_split_prepare

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

On 07/27/2017 02:07 PM, Aneesh Kumar K.V wrote:

> diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> index 8c8fb6fbdabe..b856e130c678 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> @@ -164,8 +164,6 @@ extern pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma,
>   extern void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
>   					 pgtable_t pgtable);
>   extern pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
> -extern void hash__pmdp_huge_split_prepare(struct vm_area_struct *vma,
> 
> @@ -1956,14 +1956,39 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
>   		return __split_huge_zero_page_pmd(vma, haddr, pmd);
>   	}
> 


....

> +	 */
> +	old_pmd = pmdp_invalidate(vma, haddr, pmd);
> +
> +	page = pmd_page(old_pmd);
>   	VM_BUG_ON_PAGE(!page_count(page), page);
>   	page_ref_add(page, HPAGE_PMD_NR - 1);
> -	write = pmd_write(*pmd);
> -	young = pmd_young(*pmd);
> -	soft_dirty = pmd_soft_dirty(*pmd);
> -
> -	pmdp_huge_split_prepare(vma, haddr, pmd);
> +	write = pmd_write(old_pmd);
> +	young = pmd_young(old_pmd);
> +	dirty = pmd_dirty(*pmd);

This should be

	dirty = pmd_dirty(old_pmd);


> +	soft_dirty = pmd_soft_dirty(old_pmd);
> +	/*
> +	 * withdraw the table only after we mark the pmd entry invalid
> +	 */
>   	pgtable = pgtable_trans_huge_withdraw(mm, pmd);

-aneesh

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