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Date:   Fri, 30 Jun 2023 11:58:55 -0400
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Subject: Re: [PATCH 2/2] mm: use a folio in fault_dirty_shared_page()
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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>
 <20230630121310.165700-3-zhangpeng362@huawei.com>
From:   Sidhartha Kumar <sidhartha.kumar@oracle.com>
In-Reply-To: <20230630121310.165700-3-zhangpeng362@huawei.com>
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On 6/30/23 5:13 AM, Peng Zhang wrote:
> From: ZhangPeng <zhangpeng362@huawei.com>
> 
> We can replace four implicit calls to compound_head() with one by using
> folio.
> 
> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
> ---
>   mm/memory.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 6921df44a99f..73b03706451c 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2967,20 +2967,20 @@ static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
>   {
>   	struct vm_area_struct *vma = vmf->vma;
>   	struct address_space *mapping;
> -	struct page *page = vmf->page;
> +	struct folio *folio = page_folio(vmf->page);
>   	bool dirtied;
>   	bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
>   
> -	dirtied = set_page_dirty(page);
> -	VM_BUG_ON_PAGE(PageAnon(page), page);
> +	dirtied = folio_mark_dirty(folio);
> +	VM_BUG_ON_FOLIO(folio_test_anon(folio), folio);
>   	/*
>   	 * Take a local copy of the address_space - page.mapping may be zeroed
>   	 * by truncate after unlock_page().   The address_space itself remains
>   	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
>   	 * release semantics to prevent the compiler from undoing this copying.
>   	 */
> -	mapping = folio_raw_mapping(page_folio(page));
> -	unlock_page(page);
> +	mapping = folio_raw_mapping(folio);
> +	folio_unlock(folio);
>   
>   	if (!page_mkwrite)
>   		file_update_time(vma->vm_file);
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>