From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932190AbWBVHU4 (ORCPT ); Wed, 22 Feb 2006 02:20:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932197AbWBVHU4 (ORCPT ); Wed, 22 Feb 2006 02:20:56 -0500 Received: from gold.veritas.com ([143.127.12.110]:12134 "EHLO gold.veritas.com") by vger.kernel.org with ESMTP id S932190AbWBVHUz (ORCPT ); Wed, 22 Feb 2006 02:20:55 -0500 X-IronPort-AV: i="4.02,135,1139212800"; d="scan'208"; a="55848581:sNHT31962472" Date: Wed, 22 Feb 2006 07:21:41 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Andrew Morton cc: torvalds@osdl.org, ak@suse.de, holt@sgi.com, bcasavan@sgi.com, cr@sap.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tmpfs: fix mount mpol nodelist parsing In-Reply-To: <20060221183004.72ffa011.akpm@osdl.org> Message-ID: References: <20060221183004.72ffa011.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 22 Feb 2006 07:20:55.0030 (UTC) FILETIME=[84D17960:01C63780] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 21 Feb 2006, Andrew Morton wrote: > Hugh Dickins wrote: > > > > Move the mpol= parsing to shmem_parse_mpol under CONFIG_NUMA, reject > > all its options as invalid if not NUMA. > > That's a bit irritating, really. It means that userspace needs to be > different for NUMA kernels (or more different, which is still bad). Boot > into a non-NUMA kernel and whoops, no tmpfs and quite possibly no boot. Well spotted. That was a choice that gave me pause between making it and sending the patch. But in the end I decided we might as well. Repeating what I wrote to Robin about it... I did wonder for a while whether I'd been unhelpful to make mpol= fail when not CONFIG_NUMA - tiresome for someone switching between NUMA and non-NUMA kernels. But this is an advanced option, not something for everybody's /etc/fstab; and once I realized that all but the trivial nodelist "0" would get rejected anyway if not CONFIG_NUMA, decided it is best to placate the anti-bloaters with that CONFIG_NUMA after all. > But last time I whined about this Albert had a list of fairly > reasonable-sounding reasons why filesystems shouldn't silently accept > not-understood options. > > But in this case, we _do_ understand them. We're just not going to do > anything about them. > > I just wonder if we're being as friendly as we possibly can be to admins > and distro-makers. I doubt the distro-makers will want to be putting "mpol=" options into their tmpfs lines in /etc/fstab. I hope the admins of such systems that need it can cope. But perhaps I should expand the mention of CONFIG_NUMA in tmpfs.txt, to explain the issue, and suggest that "mpol=" be used in remounts rather than automatic mounts on systems where it might be a problem. I'll dream up some wording later. > [ Vaguely suprised that tmpfs isn't using match_token()... ] I did briefly consider that back in the days when I noticed a host of fs filesystems got converted. But didn't see any point in messing with what was already working. Haven't looked recently: would it actually be a useful change to make? Hugh