From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A57FFC3F6B0 for ; Wed, 10 Aug 2022 09:44:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232256AbiHJJoG (ORCPT ); Wed, 10 Aug 2022 05:44:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231417AbiHJJn5 (ORCPT ); Wed, 10 Aug 2022 05:43:57 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CAA15142E; Wed, 10 Aug 2022 02:43:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660124636; x=1691660636; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=+g1tHa8U1L0ibLkauTiBh/SeADRVoqwRkL+l6I4l0TE=; b=KD5tS2QCDwJMQI8UA4rat5QwIhjZFuhAU3fkbBz2Qopqm39IPmlDXEB7 kpnEH+pswkbTBg2eWgNhNr6YiMxN3Hp+Qn5rpbdfqH9MMEcci/t6lGxQT xBEaXZ4cYPW9Ix3n6fwjfDzTtBt5AuIsy2VULSwPwadzrJN9L4ktKrDPD vLlT9hRei/ZdO2r5MvenMBohZmEJH/Jb9YhUNlby2H9SBCNtuhQa6IBPp 4Q/PUZt5bs+lbyWdpk/MKS33FWmY6c8WmBPO0nsShYhN6LaNW9Dbi/Qbd Gs5zBQQ641dkV1su7JsUxg9Wp/F6lsCDV1m8gmeB4VC3Pz9mTXK4/qJG+ w==; X-IronPort-AV: E=McAfee;i="6400,9594,10434"; a="289798229" X-IronPort-AV: E=Sophos;i="5.93,227,1654585200"; d="scan'208";a="289798229" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Aug 2022 02:43:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,227,1654585200"; d="scan'208";a="601757538" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by orsmga007.jf.intel.com with ESMTP; 10 Aug 2022 02:43:45 -0700 Date: Wed, 10 Aug 2022 17:38:59 +0800 From: Chao Peng To: Paolo Bonzini Cc: David Hildenbrand , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, linux-kselftest@vger.kernel.org, Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, Muchun Song Subject: Re: [PATCH v7 01/14] mm: Add F_SEAL_AUTO_ALLOCATE seal to memfd Message-ID: <20220810093859.GF862421@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220706082016.2603916-2-chao.p.peng@linux.intel.com> <472207cf-ff71-563b-7b66-0c7bea9ea8ad@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <472207cf-ff71-563b-7b66-0c7bea9ea8ad@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 05, 2022 at 07:55:38PM +0200, Paolo Bonzini wrote: > On 7/21/22 11:44, David Hildenbrand wrote: > > > > Also, I*think* you can place pages via userfaultfd into shmem. Not > > sure if that would count "auto alloc", but it would certainly bypass > > fallocate(). > > Yeah, userfaultfd_register would probably have to forbid this for > F_SEAL_AUTO_ALLOCATE vmas. Maybe the memfile_node can be reused for this, > adding a new MEMFILE_F_NO_AUTO_ALLOCATE flags? Then userfault_register > would do something like memfile_node_get_flags(vma->vm_file) and check the > result. Then we need change userfault_register uAPI for a new property flag. Userspace should still the decision-maker for this flag. > > This means moving this patch later, after "mm: Introduce memfile_notifier". Yes, it makes sense now. Chao > > Thanks, > > Paolo