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[34.90.227.64]) by smtp.gmail.com with ESMTPSA id v20-20020a170906381400b007307d099ed7sm3440458ejc.121.2022.08.11.05.27.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Aug 2022 05:27:59 -0700 (PDT) Date: Thu, 11 Aug 2022 12:27:56 +0000 From: Quentin Perret To: Sean Christopherson Cc: David Hildenbrand , Chao Peng , 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, Paolo Bonzini , Jonathan Corbet , 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, Michael Roth , mhocko@suse.com, Muchun Song , Will Deacon , Fuad Tabba Subject: Re: [PATCH v7 03/14] mm: Introduce memfile_notifier Message-ID: References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220706082016.2603916-4-chao.p.peng@linux.intel.com> <13394075-fca0-6f2b-92a2-f1291fcec9a3@redhat.com> <20220810092232.GC862421@chaop.bj.intel.com> <00f1aa03-bc82-ffce-569b-e2d5c459992c@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660220882; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=3MRcVxkQskaoR9Gu8vTdfe3SAmvath2jQNxcSxuvW1Y=; b=7M629qYXBh2rEfMsbnehHVahGwwt1o4C54IW0vzW0dklSpW9OUsEYqlP9XDhXnfJyw/+Py l5xrgvr1KBPtIbtyrIYo5k7v6SCF5fZeTEJYxIBh+B0HfVRdZjDB1J0/4u87I1Eu3wpRea D6/8WkhUQ6YrkVtAYwfBGjRa2WOoKqA= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=NHGbxl9p; spf=pass (imf19.hostedemail.com: domain of qperret@google.com designates 209.85.208.48 as permitted sender) smtp.mailfrom=qperret@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660220882; a=rsa-sha256; cv=none; b=eT2328dSM06FZG2/XM6z1LKFsq0MakbBP4aNaCe/mIXeW4dtuuLqbcDo6r6qgMglbN2Yj8 Mq8B+3ozZRuhtRZQ3Elwzt04uEh0NltUXBQXBy4SCPPHdtoHky3z+g2LCa8kHzPZbxdSs3 ArHaPWBUDVhiUahk+NhM7POP8KWvArA= X-Stat-Signature: npu4tjogi5dcka3761h5ku36793sndti X-Rspamd-Queue-Id: 824B01A0163 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=NHGbxl9p; spf=pass (imf19.hostedemail.com: domain of qperret@google.com designates 209.85.208.48 as permitted sender) smtp.mailfrom=qperret@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1660220882-648186 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: +CC Fuad On Wednesday 10 Aug 2022 at 14:38:43 (+0000), Sean Christopherson wrote: > > I understand Sean's suggestion about abstracting, but if the new name > > makes it harder to grasp and there isn't really an alternative to memfd > > in sight, I'm not so sure I enjoy the tried abstraction here. > > ARM's pKVM implementation is potentially (hopefully) going to switch to this API > (as a consumer) sooner than later. If they anticipate being able to use memfd, > then there's unlikely to be a second backing type any time soon. > > Quentin, Will? Yep, Fuad is currently trying to port the pKVM mm stuff on top of this series to see how well it fits, so stay tuned. I think there is still some room for discussion around page conversions (private->shared etc), and we'll need a clearer idea of what the code might look like to have a constructive discussion, but so far it does seem like using a memfd (the new private one or perhaps just memfd_secret, to be discussed) + memfd notifiers is a promising option.