From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f47.google.com (mail-wg0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id 010496B0069 for ; Mon, 20 Oct 2014 14:15:01 -0400 (EDT) Received: by mail-wg0-f47.google.com with SMTP id x13so6030240wgg.18 for ; Mon, 20 Oct 2014 11:15:00 -0700 (PDT) Received: from mail-wi0-x234.google.com (mail-wi0-x234.google.com. [2a00:1450:400c:c05::234]) by mx.google.com with ESMTPS id fl4si9306379wib.99.2014.10.20.11.14.59 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 20 Oct 2014 11:14:59 -0700 (PDT) Received: by mail-wi0-f180.google.com with SMTP id em10so7099944wid.13 for ; Mon, 20 Oct 2014 11:14:59 -0700 (PDT) Message-ID: <5445511D.1090603@redhat.com> Date: Mon, 20 Oct 2014 20:14:53 +0200 From: Paolo Bonzini 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> <54429521.80402@intel.com> In-Reply-To: <54429521.80402@intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen , 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 , Peter Zijlstra , Sasha Levin On 10/18/2014 06:28 PM, Dave Hansen wrote: > > 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. I agree with Dave (I thought I disagreed, but I changed my mind while writing down my thoughts). Just define mm_forbids_zeropage in arch/s390/include/asm, and make it return mm->context.use_skey---with a comment explaining how this is only for processes that use KVM, and then only for guests that use storage keys. Paolo (who was just taught what storage keys really are) -- 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