Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760789AbZCMREx (ORCPT ); Fri, 13 Mar 2009 13:04:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759187AbZCMRBQ (ORCPT ); Fri, 13 Mar 2009 13:01:16 -0400 Received: from mga11.intel.com ([192.55.52.93]:1036 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759710AbZCMRBO (ORCPT ); Fri, 13 Mar 2009 13:01:14 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.38,358,1233561600"; d="scan'208";a="672745917" Subject: Re: [tip:x86/urgent] VM, x86, PAT: Change is_linear_pfn_mapping to not use vm_pgoff From: "Pallipadi, Venkatesh" To: Nick Piggin 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" In-Reply-To: <20090313162530.GA7118@wotan.suse.de> References: <20090313004527.GA7176@linux-os.sc.intel.com> <20090313162530.GA7118@wotan.suse.de> Content-Type: text/plain Date: Fri, 13 Mar 2009 10:00:07 -0700 Message-Id: <1236963607.4529.111.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 (2.24.3-1.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2026 Lines: 47 On Fri, 2009-03-13 at 09:25 -0700, Nick Piggin wrote: > On Fri, Mar 13, 2009 at 04:03:39AM +0000, Pallipadi, Venkatesh wrote: > > Commit-ID: 4bb9c5c02153dfc89a6c73a6f32091413805ad7d > > Gitweb: http://git.kernel.org/tip/4bb9c5c02153dfc89a6c73a6f32091413805ad7d > > Author: Pallipadi, Venkatesh > > AuthorDate: Thu, 12 Mar 2009 17:45:27 -0700 > > Commit: Ingo Molnar > > CommitDate: Fri, 13 Mar 2009 04:28:50 +0100 > > > > /* > > + * pfnmap vmas that are fully mapped at mmap time (not mapped on fault). > > + * Used by x86 PAT to identify such PFNMAP mappings and optimize their handling. > > + * Note VM_INSERTPAGE flag is overloaded here. i.e, > > + * VM_INSERTPAGE && !VM_PFNMAP implies > > + * The vma has had "vm_insert_page()" done on it > > + * VM_INSERTPAGE && VM_PFNMAP implies > > + * The vma is PFNMAP with full mapping at mmap time > > + */ > > +#define VM_PFNMAP_AT_MMAP (VM_INSERTPAGE | VM_PFNMAP) > > This is really ugly IMO. Either it should be its own bit, or if you want > to reduce usage of bits, then set aside some bits to represent a set of > vma types, and convert existing code over to use that. > > 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). 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. Thanks, Venki -- 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/