Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753607AbZCNCwy (ORCPT ); Fri, 13 Mar 2009 22:52:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751623AbZCNCwo (ORCPT ); Fri, 13 Mar 2009 22:52:44 -0400 Received: from mx2.suse.de ([195.135.220.15]:50014 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456AbZCNCwn (ORCPT ); Fri, 13 Mar 2009 22:52:43 -0400 Date: Sat, 14 Mar 2009 03:52:38 +0100 From: Nick Piggin To: "Pallipadi, Venkatesh" Cc: "mingo@redhat.com" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "elendil@planet.nl" , "thellstrom@vmware.com" , "ebiederm@xmission.com" , "tglx@linutronix.de" , "mingo@elte.hu" , "linux-tip-commits@vger.kernel.org" Subject: Re: [tip:x86/urgent] VM, x86, PAT: Change is_linear_pfn_mapping to not use vm_pgoff Message-ID: <20090314025238.GA32065@wotan.suse.de> References: <20090313004527.GA7176@linux-os.sc.intel.com> <20090313162530.GA7118@wotan.suse.de> <1236963607.4529.111.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1236963607.4529.111.camel@localhost.localdomain> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 35 On Fri, Mar 13, 2009 at 10:00:07AM -0700, Pallipadi, Venkatesh wrote: > On Fri, 2009-03-13 at 09:25 -0700, Nick Piggin wrote: > > Why not just use another vm_flag for 2.6.29 and earlier (we have 2 left), > > then do some flag rationalisation in 2.6.30? > > > > But I do like just avoiding these games entirely and encoding it > > explicitly. > > > > Totally agree that this is ugly. But, I didn't like taking away one bit > for such a light usage. VM_INSERTPAGE is hardly ever used in the kernel > (wherever it is used, it is checked along with VM_PFNMAP). That is a concern, but I think it makes the patch more intrusive than a simple fix that might possibly introduce a bug. So for 2.6.29 we have spare flags so can use one of those for the fix. > OK. I will resend the patch with taking away one of the available bits. > But, I feel we need to do some multiplexing here, in a clean manner, for > future. That would always be appreciated. There are probably several flags that can go away (eg. VM_RESERVED, VM_INSERTPAGE), others that can be merged (eg nommu flags with mmu flags), others that can be one scalar value rather than several binary values etc. Also, if worst comes to worst, I think we could probably make vm_flags 64-bit on 32-bit compiles to get another 32 bits. Of course I'd rather not until no other options left for reducing flags ;) -- 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/