From mboxrd@z Thu Jan 1 00:00:00 1970 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 Subject: Re: [PATCH] mm: use pagevec to rotate reclaimable page In-Reply-To: <20070913193711.ecc825f7.akpm@linux-foundation.org> References: <6.0.0.20.2.20070907113025.024dfbb8@172.19.0.2> <20070913193711.ecc825f7.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org