Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756284AbZCLXV2 (ORCPT ); Thu, 12 Mar 2009 19:21:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754832AbZCLXVT (ORCPT ); Thu, 12 Mar 2009 19:21:19 -0400 Received: from ti-out-0910.google.com ([209.85.142.185]:60148 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754037AbZCLXVS (ORCPT ); Thu, 12 Mar 2009 19:21:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:in-reply-to:references:x-mailer :mime-version:content-type:content-transfer-encoding; b=na5bzZOnppqIKDJG/hy+Cz1fvgX3gs7FuCNXQIO+W3QoYxw7RlREx3TkkPHXK8q/5w uhBXM+FygvK1Nuqz/Di2QY1be57f7/n5xL93aoUXGkzwepROmQWzpKaPB3jKFpJ0976C 1SfmB0/L+Z7dMTj0HvcVFprmA/wX81VhIXSDM= Date: Fri, 13 Mar 2009 08:20:51 +0900 From: Minchan Kim To: Peter Zijlstra Cc: Jamie Lokier , uClinux development list , Andrew Morton , David Howells , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [uClinux-dev] RE: [PATCH] NOMMU: Pages allocated to a ramfs inode's pagecache may get wrongly discarded Message-Id: <20090313082051.5eaa11a3.minchan.kim@barrios-desktop> In-Reply-To: <1236858608.22914.3689.camel@twins> References: <20090311153034.9389.19938.stgit@warthog.procyon.org.uk> <20090311170840.2f136849.akpm@linux-foundation.org> <5DC5324CE00E4D4494EE5F031E354E9501CE9C0F@BUDMLVEM03.e2k.ad.ge.com> <20090312112953.GD6995@shareable.org> <1236858608.22914.3689.camel@twins> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2096 Lines: 56 Hi, Peter. On Thu, 12 Mar 2009 12:50:08 +0100 Peter Zijlstra wrote: > On Thu, 2009-03-12 at 11:29 +0000, Jamie Lokier wrote: > > Berkhan, Enrik (GE Infra, Oil & Gas) wrote: > > > Andrew Morton wrote: > > > > On Wed, 11 Mar 2009 15:30:35 +0000 > > > > David Howells wrote: > > > >> From: Enrik Berkhan > > > >> > > > >> The solution is to mark the pages dirty at the point of allocation by > > > >> the truncation code. > > > > > > > > Was there a specific reason for using the low-level SetPageDirty()? > > > > > > No, no specific reason. It was just my first try of a fix after spotting > > > the problem. After a short discussion with David, we decided to wait for > > > others' comments on using the low-/high-level approach. > > > > Tangentially related... > > > > Does the vm pageout logic include or skip these "dirty" pages looking > > for candidates to flush to storage? What about with MMU? > > Includes them, regular pageout will try to do the writeout to clean them > and then discard them. > > The ramfs stuff is rather icky in that it adds the pages to the aging > list, marks them dirty, but does not provide a writeout method. > > This will make the paging code scan over them (continuously) trying to > clean them, failing that (lack of writeout method) and putting them back > on the list. It ins't true any more. UNEVICTABLE_LRU will move ramfs's page from LRU to unevictable list. Couldn't we solve this problem if NOMMU can support CONFIG_UNEVICTABLE_LRU ? > -- > 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/ -- Kinds 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/