Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753218AbZCMH6D (ORCPT ); Fri, 13 Mar 2009 03:58:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753867AbZCMH5s (ORCPT ); Fri, 13 Mar 2009 03:57:48 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:37536 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752875AbZCMH5s (ORCPT ); Fri, 13 Mar 2009 03:57:48 -0400 Subject: Re: [PATCH] NOMMU: Pages allocated to a ramfs inode's pagecache may get wrongly discarded From: Peter Zijlstra To: KOSAKI Motohiro Cc: Andrew Morton , David Howells , torvalds@linux-foundation.org, Enrik.Berkhan@ge.com, uclinux-dev@uclinux.org, linux-kernel@vger.kernel.org In-Reply-To: <20090313105618.43DF.A69D9226@jp.fujitsu.com> References: <24030.1236860724@redhat.com> <20090312124323.ad0dbd68.akpm@linux-foundation.org> <20090313105618.43DF.A69D9226@jp.fujitsu.com> Content-Type: text/plain Date: Fri, 13 Mar 2009 08:57:16 +0100 Message-Id: <1236931036.5188.80.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.25.92 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1243 Lines: 32 On Fri, 2009-03-13 at 11:03 +0900, KOSAKI Motohiro wrote: > Hi > > > > Which as Peter points out: > > > > > > 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. > > > > > > Not requiring the pages to be added to the LRU would be a really good idea. > > > They are not discardable, be it in MMU or NOMMU mode, except when the inode > > > itself is discarded. > > > > Yep, these pages shouldn't be on the LRU at all. I guess that will > > require some tweaks to core filemap.c code. > > IMHO, UNEVICTABLE_LRU already does lru isolation. > only rest prblem is, getting rid of "depends on MMU" line in mm/Kconfig. > > Am I missing anything? Yes, the need to take something off that shouldn't be there to begin with. -- 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/