Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752203Ab0LTCtO (ORCPT ); Sun, 19 Dec 2010 21:49:14 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:58543 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751593Ab0LTCtN convert rfc822-to-8bit (ORCPT ); Sun, 19 Dec 2010 21:49:13 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=XB64yiduYgz8mmEZ8ndsZbLYSNF/EarmoZIjZMHPRNulV2Bk0LA4IWWRnLEamtOFHn cFo2FDsc0p1NgyrKp+lw+EEY/nIFiR3LaN5tCa+9b7fIvtqdDhrQ98KAXUMkFICl8IXy Mpe/mlAFK+5/1gX7P6w8B2TSNNN1GL0r2SWkQ= 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 To: KOSAKI Motohiro Cc: Andrew Morton , linux-mm , LKML , Nick Piggin , Al Viro Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1921 Lines: 59 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? > >> >> > cleancache_flush_page() doesn't cause NULL deref? > > > > -- Kind regards, Minchan Kim -- 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/