From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id 910476B0069 for ; Sat, 18 Oct 2014 12:28:22 -0400 (EDT) Received: by mail-pd0-f173.google.com with SMTP id g10so2461500pdj.18 for ; Sat, 18 Oct 2014 09:28:22 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTP id pp3si3688095pdb.218.2014.10.18.09.28.19 for ; Sat, 18 Oct 2014 09:28:20 -0700 (PDT) Message-ID: <54429521.80402@intel.com> Date: Sat, 18 Oct 2014 09:28:17 -0700 From: Dave Hansen MIME-Version: 1.0 Subject: Re: [PATCH 2/4] mm: introduce new VM_NOZEROPAGE flag References: <1413554990-48512-1-git-send-email-dingel@linux.vnet.ibm.com> <1413554990-48512-3-git-send-email-dingel@linux.vnet.ibm.com> <54419265.9000000@intel.com> <20141018164928.2341415f@BR9TG4T3.de.ibm.com> In-Reply-To: <20141018164928.2341415f@BR9TG4T3.de.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dominik Dingel Cc: Andrew Morton , linux-mm@kvack.org, Mel Gorman , Michal Hocko , Rik van Riel , Andrea Arcangeli , Andy Lutomirski , "Aneesh Kumar K.V" , Bob Liu , Christian Borntraeger , Cornelia Huck , Gleb Natapov , Heiko Carstens , "H. Peter Anvin" , Hugh Dickins , Ingo Molnar , Jianyu Zhan , Johannes Weiner , "Kirill A. Shutemov" , Konstantin Weitz , kvm@vger.kernel.org, linux390@de.ibm.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky , Paolo Bonzini , Peter Zijlstra , Sasha Levin On 10/18/2014 07:49 AM, Dominik Dingel wrote: > On Fri, 17 Oct 2014 15:04:21 -0700 > Dave Hansen wrote: >> Is there ever a time where the VMAs under an mm have mixed VM_NOZEROPAGE >> status? Reading the patches, it _looks_ like it might be an all or >> nothing thing. > > Currently it is an all or nothing thing, but for a future change we might want to just > tag the guest memory instead of the complete user address space. I think it's a bad idea to reserve a flag for potential future use. If you _need_ it in the future, let's have the discussion then. For now, I think it should probably just be stored in the mm somewhere. >> Full disclosure: I've got an x86-specific feature I want to steal a flag >> for. Maybe we should just define another VM_ARCH bit. >> > > So you think of something like: > > #if defined(CONFIG_S390) > # define VM_NOZEROPAGE VM_ARCH_1 > #endif > > #ifndef VM_NOZEROPAGE > # define VM_NOZEROPAGE VM_NONE > #endif > > right? Yeah, something like that. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org