linux-kernel - Re: [PATCH -mm v2] mm: add page_check_address

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Message-ID: <20151124094659.GF29014@esperanza>
Date:	Tue, 24 Nov 2015 12:46:59 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
CC:	"Kirill A. Shutemov" <kirill@...temov.name>,
	Andrew Morton <akpm@...ux-foundation.org>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -mm v2] mm: add page_check_address_transhuge helper

On Tue, Nov 24, 2015 at 12:36:17PM +0300, Vladimir Davydov wrote:
...
> I think we'd better compile out page_check_address_transhuge altogether if
> CONFIG_TRANSPARENT_HUGEPAGE is disabled and use page_check_address instead.
> This would also reduce the kernel size a bit.

Sergey, could you please check if the patch below fixes build for you?

Thanks,
Vladimir

> ---
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index b9eedc63e9e6..77d1ba57d495 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -219,9 +219,20 @@ static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
>   * Used by idle page tracking to check if a page was referenced via page
>   * tables.
>   */
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
>  				  unsigned long address, pmd_t **pmdp,
>  				  pte_t **ptep, spinlock_t **ptlp);
> +#else
> +static inline bool page_check_address_transhuge(struct page *page,
> +				struct mm_struct *mm, unsigned long address,
> +				pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp)
> +{
> +	*ptep = page_check_address(page, mm, address, ptlp, 0);
> +	*pmdp = NULL;
> +	return !!*ptep;
> +}
> +#endif
>  
>  /*
>   * Used by swapoff to help locate where page is expected in vma.
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 27916086ac50..6f371261dd12 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -798,6 +798,7 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
>  	return 1;
>  }
>  
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  /*
>   * Check that @page is mapped at @address into @mm. In contrast to
>   * page_check_address(), this function can handle transparent huge pages.
> @@ -885,6 +886,7 @@ found:
>  	*ptlp = ptl;
>  	return true;
>  }
> +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  
>  struct page_referenced_arg {
>  	int mapcount;
> 
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