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Date: Fri, 19 Dec 2008 11:21:25 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: Corruption with O_DIRECT and unaligned user buffers
Message-Id: <20081219112125.75bbda2b.kamezawa.hiroyu@jp.fujitsu.com>
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References: <491DAF8E.4080506@quantum.com>
	<200811191526.00036.nickpiggin@yahoo.com.au>
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Sender: owner-linux-mm@kvack.org
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>, Tim LaBerge <tim.laberge@quantum.com>, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
List-ID: <linux-mm.kvack.org>

On Thu, 18 Dec 2008 16:29:52 +0100
Andrea Arcangeli <aarcange@redhat.com> wrote:

> @@ -484,11 +476,34 @@
>  	if (page) {
>  		get_page(page);
>  		page_dup_rmap(page);
> +		if (is_cow_mapping(vm_flags) && PageAnon(page)) {
> +			if (unlikely(TestSetPageLocked(page)))
> +				forcecow = 1;
> +			else {
> +				if (unlikely(page_count(page) !=
> +					     page_mapcount(page)
> +					     + !!PageSwapCache(page)))
> +					forcecow = 1;
> +				unlock_page(page);
> +			}
> +		}
>  		rss[!!PageAnon(page)]++;
>  	}
 - Why do you check only Anon rather than all MAP_PRIVATE mappings ?

Thanks,
-Kame


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