From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 6A0F86B00AE for ; Sun, 19 Dec 2010 21:32:18 -0500 (EST) Received: from m1.gw.fujitsu.co.jp ([10.0.50.71]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id oBK2WFJQ010620 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 20 Dec 2010 11:32:16 +0900 Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id BDDDB45DE5F for ; Mon, 20 Dec 2010 11:32:15 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id A428F45DE56 for ; Mon, 20 Dec 2010 11:32:15 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 93BD1E38009 for ; Mon, 20 Dec 2010 11:32:15 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 60DF9E08003 for ; Mon, 20 Dec 2010 11:32:15 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC 5/5] truncate: Remove unnecessary page release In-Reply-To: References: <20101220112227.E566.A69D9226@jp.fujitsu.com> Message-Id: <20101220113239.E56C.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Date: Mon, 20 Dec 2010 11:32:13 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , linux-mm , LKML , Nick Piggin , Al Viro List-ID: > On Mon, Dec 20, 2010 at 11:21 AM, KOSAKI Motohiro > wrote: > >> This patch series changes remove_from_page_cache's page ref counting > >> rule. page cache ref count is decreased in remove_from_page_cache. > >> So we don't need call again in caller context. > >> > >> Cc: Nick Piggin > >> Cc: Al Viro > >> Cc: linux-mm@kvack.org > >> Signed-off-by: Minchan Kim > >> --- > >> =A0mm/truncate.c | =A0 =A01 - > >> =A01 files changed, 0 insertions(+), 1 deletions(-) > >> > >> diff --git a/mm/truncate.c b/mm/truncate.c > >> index 9ee5673..8decb93 100644 > >> --- a/mm/truncate.c > >> +++ b/mm/truncate.c > >> @@ -114,7 +114,6 @@ truncate_complete_page(struct address_space *mappi= ng, struct page *page) > >> =A0 =A0 =A0 =A0* calls cleancache_put_page (and note page->mapping is = now NULL) > >> =A0 =A0 =A0 =A0*/ > >> =A0 =A0 =A0 cleancache_flush_page(mapping, page); > >> - =A0 =A0 page_cache_release(page); =A0 =A0 =A0 /* pagecache ref */ > >> =A0 =A0 =A0 return 0; > > > > Do we _always_ have stable page reference here? IOW, I can assume >=20 > I think so. > Because the page is locked so caller have to hold a ref to unlock it. Hmm... Perhaps, I'm missing something. But I think __memory_failure() only lock= =20 compaund_head page. not all. example. >=20 > > cleancache_flush_page() doesn't cause NULL deref? -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org