Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752454Ab0LTDDl (ORCPT ); Sun, 19 Dec 2010 22:03:41 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:46978 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752155Ab0LTDDk convert rfc822-to-8bit (ORCPT ); Sun, 19 Dec 2010 22:03:40 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Minchan Kim Subject: Re: [RFC 5/5] truncate: Remove unnecessary page release Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , linux-mm , LKML , Nick Piggin , Al Viro 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: 8BIT X-Mailer: Becky! ver. 2.50.07 [ja] Date: Mon, 20 Dec 2010 12:03:35 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2374 Lines: 68 > 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 > >> >> --- > >> >> ?mm/truncate.c | ? ?1 - > >> >> ?1 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 *mapping, struct page *page) > >> >> ? ? ? ?* calls cleancache_put_page (and note page->mapping is now NULL) > >> >> ? ? ? ?*/ > >> >> ? ? ? cleancache_flush_page(mapping, page); > >> >> - ? ? page_cache_release(page); ? ? ? /* pagecache ref */ > >> >> ? ? ? 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 ?__memory_failure() only lock > > 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? I dunno, really. My five miniture grep found following logic. therefore I asked you. __memory_failure() { p = pfn_to_page(pfn); hpage = compound_head(p); (snip) res = -EBUSY; for (ps = error_states;; ps++) { if ((p->flags & ps->mask) == ps->res) { res = page_action(ps, p, pfn); // call truncate here break; } } out: unlock_page(hpage); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/