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Date:   Fri, 30 Jun 2023 12:03:37 -0400
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Subject: Re: [PATCH 1/2] mm: remove page_rmapping()
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To:     Peng Zhang <zhangpeng362@huawei.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Cc:     willy@infradead.org, akpm@linux-foundation.org,
        wangkefeng.wang@huawei.com, sunnanyong@huawei.com
References: <20230630121310.165700-1-zhangpeng362@huawei.com>
 <20230630121310.165700-2-zhangpeng362@huawei.com>
From:   Sidhartha Kumar <sidhartha.kumar@oracle.com>
In-Reply-To: <20230630121310.165700-2-zhangpeng362@huawei.com>
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On 6/30/23 5:13 AM, Peng Zhang wrote:
> From: ZhangPeng <zhangpeng362@huawei.com>
> 
> After converting the last user to folio_raw_mapping(), we can safely
> remove the function.
> 
> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
> ---
>   include/linux/mm.h | 1 -
>   mm/memory.c        | 2 +-
>   mm/util.c          | 6 ------
>   3 files changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9ecb8b9c07f6..8c7eba7370b2 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2129,7 +2129,6 @@ static inline void *folio_address(const struct folio *folio)
>   	return page_address(&folio->page);
>   }
>   
> -extern void *page_rmapping(struct page *page);
>   extern pgoff_t __page_file_index(struct page *page);
>   
>   /*
> diff --git a/mm/memory.c b/mm/memory.c
> index 21fab2727209..6921df44a99f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2979,7 +2979,7 @@ static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
>   	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
>   	 * release semantics to prevent the compiler from undoing this copying.
>   	 */


	struct page *page = vmf->page;
	
	...

	dirtied = set_page_dirty(page);
	VM_BUG_ON_PAGE(PageAnon(page), page);

Can this earlier part of the function be converted to folios so a folio 
can be passed directly in folio_raw_mapping()?
> -	mapping = page_rmapping(page);
> +	mapping = folio_raw_mapping(page_folio(page));
>   	unlock_page(page);
>   
>   	if (!page_mkwrite)
> diff --git a/mm/util.c b/mm/util.c
> index dd12b9531ac4..5e9305189c3f 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -734,12 +734,6 @@ void *vcalloc(size_t n, size_t size)
>   }
>   EXPORT_SYMBOL(vcalloc);
>   
> -/* Neutral page->mapping pointer to address_space or anon_vma or other */
> -void *page_rmapping(struct page *page)
> -{
> -	return folio_raw_mapping(page_folio(page));
> -}
> -
>   struct anon_vma *folio_anon_vma(struct folio *folio)
>   {
>   	unsigned long mapping = (unsigned long)folio->mapping;