linux-kernel - Re: [PATCH] shmem: replace_page must flush

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Message-ID: <20120608084033.GA21818@schnuecks.de>
Date:	Fri, 8 Jun 2012 10:40:33 +0200
From:	Simon Baatz <gmbnomis@...il.com>
To:	Hugh Dickins <hughd@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Stephane Marchesin <marcheu@...omium.org>,
	Andi Kleen <andi@...stfloor.org>,
	Dave Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Rob Clark <rob.clark@...aro.org>,
	Cong Wang <xiyou.wangcong@...il.com>, linux-mm@...ck.org,
	linux-fsdevel@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] shmem: replace_page must flush_dcache and others

Hi Hugh,

On Thu, May 31, 2012 at 03:31:27PM -0700, Hugh Dickins wrote:
> * shmem_replace_page must flush_dcache_page after copy_highpage [akpm]

>  
> -	*pagep = newpage;
>  	page_cache_get(newpage);
>  	copy_highpage(newpage, oldpage);
> +	flush_dcache_page(newpage);
>  

Couldn't we use the lighter flush_kernel_dcache_page() here (like in
fs/exec.c copy_strings())?  If I got this correctly, the page is
copied via the kernel mapping and thus, only the kernel mapping needs
to be flushed.

- Simon
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