From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 7951D6B00B2 for ; Sun, 19 Dec 2010 21:49:14 -0500 (EST) Received: by iyj17 with SMTP id 17so1917531iyj.14 for ; Sun, 19 Dec 2010 18:49:13 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20101220113239.E56C.A69D9226@jp.fujitsu.com> References: <20101220112227.E566.A69D9226@jp.fujitsu.com> <20101220113239.E56C.A69D9226@jp.fujitsu.com> Date: Mon, 20 Dec 2010 11:49:12 +0900 Message-ID: Subject: Re: [RFC 5/5] truncate: Remove unnecessary page release From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: 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 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 *mapp= ing, 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 lo= ck > compaund_head page. not all. example. 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? > >> >> > cleancache_flush_page() doesn't cause NULL deref? > > > > --=20 Kind regards, Minchan Kim -- 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