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Message-Id: <6.0.0.20.2.20070914162337.037e82e0@172.19.0.2>
Date: Fri, 14 Sep 2007 16:42:01 +0900
From: Hisashi Hifumi <hifumi.hisashi@....ntt.co.jp>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] mm: use pagevec to rotate reclaimable page
Thank you for your comment.
At 11:37 07/09/14, Andrew Morton wrote:
>The page_count() test here is a bit of a worry, too. Why do we need it?
>The caller must have pinned the page in some fashion else we couldn't use
>it safely in this function at all.
>
>I assume that you discovered that once we've cleared PageWriteback(), the
>page can get reclaimed elsewhere? If so, that could still happen
>immediately after the page_count() test. It's all a bit of a worry.
>Deferring the ClearPageWriteback() will fix any race concerns, but I do
>think that we need to take a ref on the page for the pagevec ownership.
>
Actually, I considered taking a ref to pin pages. But this could prevent
the page
reclaiming activity so I did not use it.
I reflect your comment and send you modified patch.
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