From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 850856B00B6 for ; Sun, 19 Dec 2010 22:03:41 -0500 (EST) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id oBK33ccV024087 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 20 Dec 2010 12:03:38 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 6FE3245DE61 for ; Mon, 20 Dec 2010 12:03:38 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 4AECE45DE63 for ; Mon, 20 Dec 2010 12:03:38 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 33ACDE08001 for ; Mon, 20 Dec 2010 12:03:38 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id E68E51DB8037 for ; Mon, 20 Dec 2010 12:03:37 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC 5/5] truncate: Remove unnecessary page release In-Reply-To: References: <20101220113239.E56C.A69D9226@jp.fujitsu.com> Message-Id: <20101220120218.E56F.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 12:03:35 +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 11:32 AM, KOSAKI Motohiro > wrote: > >> On Mon, Dec 20, 2010 at 11:21 AM, KOSAKI Motohiro > >> wrote: > >> >> This patch series changes remove_from_page_cache's page ref countin= g > >> >> 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 *ma= pping, 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 > >> > >> 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 =A0__memory_failure() only = lock > > compaund_head page. not all. example. >=20 > The page passed truncate_complete_page is only head page? > Is it possible to pass the page which isn't head of compound in > truncate_complete_page? I dunno, really. My five miniture grep found following logic. therefore I a= sked you. __memory_failure() { p =3D pfn_to_page(pfn); hpage =3D compound_head(p); (snip) res =3D -EBUSY; for (ps =3D error_states;; ps++) { if ((p->flags & ps->mask) =3D=3D ps->res) { res =3D page_action(ps, p, pfn); // call truncate = here break; } } out: unlock_page(hpage); } -- 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