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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0584ACA5FD2 for ; Thu, 1 Oct 2026 14:17:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ABFB76B008C; Thu, 1 Oct 2026 10:17:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A70B26B0092; Thu, 1 Oct 2026 10:17:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 960B56B0093; Thu, 1 Oct 2026 10:17:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 6C8316B008C for ; Thu, 1 Oct 2026 10:17:50 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 94C7512045F for ; Thu, 1 Oct 2026 14:17:49 +0000 (UTC) X-FDA: 85274261058.29.46DE27A Received: from mail-dl2-f33.google.com (mail-dl2-f33.google.com [74.125.229.161]) by imf05.hostedemail.com (Postfix) with ESMTP id AC4CC100002 for ; Thu, 1 Oct 2026 14:17:47 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=cvjRgWYV; spf=pass (imf05.hostedemail.com: domain of jgg@ziepe.ca designates 74.125.229.161 as permitted sender) smtp.mailfrom=jgg@ziepe.ca; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790864267; 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=xDMyZjpmBuMrFbLISKqTNyCUa2kXcFY6ppx5n8yKikE=; b=S50YpS4mxzUBzw10t7O5SqYXz25MfiTwK2U7IXuphmMMr4EA+KrmvVSDhWCguvAM3wnFv8 mbnWYgICXQU1ci5qrcxDeA8e0xAUe0T/uMK2Sk43wMZPfPvMo4INI+qizFMNbJZm2XfUVH 7ClhUlWPEEgrQoxJqtzaiimptXdLjxI= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790864267; b=KoteFpt+bhpiSlX4zKAQQ1xwLQpgupgm+xR0cxUv51/1qSO7o0BRzyXU5Lspl2u3b129CO 4zIpsQGnyKqpIa+r38Q7O1UTF5p9L9XEqnUC5HT4s5VZeN8HQiZ9ef7/Vy+zUnoKigsjgF zatzznI0cV8q6NhDbO9BrdDsaTpHSfE= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=cvjRgWYV; spf=pass (imf05.hostedemail.com: domain of jgg@ziepe.ca designates 74.125.229.161 as permitted sender) smtp.mailfrom=jgg@ziepe.ca; dmarc=none Received: by mail-dl2-f33.google.com with SMTP id a92af1059eb24-1438e88300cso6808088c88.0 for ; Thu, 01 Oct 2026 07:17:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1790864266; x=1791469066; darn=kvack.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=xDMyZjpmBuMrFbLISKqTNyCUa2kXcFY6ppx5n8yKikE=; b=cvjRgWYV2Z8Yo7FXv8asLpDGlu/3Tk2Bbo1vLNjl8Vb4qciWNbql7VOrD+llwB17Vb bus4ZWzlODoG0K26XOfHajDTS1hZ8xGDOj9LjcVXbgQHuXmCY4sGsnB6tecxAygXnl3v z5qL7B2lLItsvpKEuIjJg5Mq1pU1g5TZQcGeGqwQkB4a6wI86XElMoRidUSHhJ6fOTHr 7dWRVkBB32dz8yUYwH8/5oSNRpzzs3nfsKPG158SMNhw1KRt4bnZSGFOhjn6xfYIn2NE yyJUF06zfwSDiXUgH/ZGR0YA1SPbaElaHUCHod+Lv0DpTWYR0U9uaKK5+hBjg5cgqivk JBOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790864266; x=1791469066; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=xDMyZjpmBuMrFbLISKqTNyCUa2kXcFY6ppx5n8yKikE=; b=dF+CC2086F9sHAO2wb9Eu9hI1vKXx2oTP/IH4cE72hNHDYRYI/EjuQ1NP4vDrRkxu3 geXL3XB2Hd/oQgNR4XGAIKfrhnsVs2/HnlrIV14lFnFE/Mv7kGaaBa1jkNzUpuzMosgH OQY6LKsaAb7kcU3lrFrzd+b4cgdDogQJnBXAiuNF7d1UmjxmtpRfR3SjpmEn8ei6CGbZ VWdjCPL8+yA2g1xbOWt2XaU9ESNHJjbjKVmwgnsbUZM053UDxNEiO/tnwibbxkb5HxO0 H3ak/Uqftz3gFOX7vM8RjvCrFm/WgNyKncnNkEPivTzb/R/bvoXKXzqZWQ9YqI6i+I3O GQTg== X-Forwarded-Encrypted: i=1; AKwUvByWi+s/+SiQuIedQsRq3mVyJ0MpUw9nHD4ze0mT9pqtPJTvRgoPGeGKn6ByTYzV8LwuKFe7OlhUhw==@kvack.org X-Gm-Message-State: AFuF++mYWxaruPqw6bsd/9nTgwp+1s3NMnsKiVRDj1JMTqiv7fnBODdI ps9iQ21Pj6avTbbWOIw6DgBXB6ZnqoOVvgTtdixm484+C4MUDlVgB/N0HJU/LWlTn/A= X-Gm-Gg: AYBFou0PQ3HRpyL9tim2DZDYNN4pSzfLvd37q2bTlk3aBi6dzA4Dd3g0k2yd3wqzLZY AJ2p6541jnVZHTDExqZPEw6XzpMRZAnH6xPXCpBGXALYmSKmRQmbuqaAKTbEYuzQI8rnGdzWvL0 W5ncCI2VNlj3DOySmyFi+sSfiim6wXC2I7StHnlWcb3c2ekzZIN/KaF1Nm/yo7IXjO3/sMh9TVP yJgnEOwCRo5Xo5hybaEYsSmlxw8sGgcW/QdvQoYOH7Mkd6VbXM4VMdnjJ9f4dKqdRcS8h3g3FOX 7dgpP2D6Fcwjo0GPVK+Mu2jvO+KqGAeVh4ReMY3a04AX5uQGJ6ZViw/GfX0hqD3fJfLBG7yKYAk pHQKq48Gp19/C+XzPD9rIkXcjIJOt6KzOp3Yw25KxLQC8BUoT5UmCe1giPHXQQJl/v0lkBSbhqa Ah6gaGGV2gRYiuL3rLGF/AtP3f6OFIFcKk1DwNNCQ83hoM5BGLUhvPFYA= X-Received: by 2002:a05:7022:ed02:b0:147:5149:d12d with SMTP id a92af1059eb24-14d33f39e14mr4209784c88.18.1790864264892; Thu, 01 Oct 2026 07:17:44 -0700 (PDT) Received: from ziepe.ca ([130.41.10.202]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-14df3ed1adcsm6451579c88.10.2026.10.01.07.17.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Oct 2026 07:17:44 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xCHbT-0000000EHOj-0Nin; Thu, 01 Oct 2026 11:17:43 -0300 Date: Thu, 1 Oct 2026 11:17:43 -0300 From: Jason Gunthorpe To: David Woodhouse Cc: ackerleytng@google.com, Hugh Dickins , Baolin Wang , Andrew Morton , Sean Christopherson , Paolo Bonzini , David Hildenbrand , Jonathan Corbet , Shuah Khan , Randy Dunlap , Shuah Khan , vannapurve@google.com, erdemaktas@google.com, jxgao@google.com, rientjes@google.com, fvdl@google.com, jthoughton@google.com, tarunsahu@google.com, pratyush@kernel.org, fuad.tabba@linux.dev, Gregory Price , yan.y.zhao@intel.com, michael.roth@amd.com, suzuki.poulose@arm.com, Christian Brauner , Nicolin Chen , Xu Yilun , aik@amd.com, aneesh.kumar@kernel.org, Vlastimil Babka , Fred Griffoul , Connor Williamson , kernel-team@android.com, kernel-team@meta.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 01/17] mm: shmem: Implement guest_memfd provider operations for tmpfs Message-ID: <20261001141743.GB3019323@ziepe.ca> References: <20260925-gmem-tmpfs-backend-v1-0-d36159822d18@google.com> <20260925-gmem-tmpfs-backend-v1-1-d36159822d18@google.com> <9292b27b8f48c515bee3246cf3b3a60762302186.camel@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9292b27b8f48c515bee3246cf3b3a60762302186.camel@infradead.org> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AC4CC100002 X-Stat-Signature: m7y1d53wm6itrwfqxxfpn7bckfre73yy X-HE-Tag: 1790864267-431228 X-HE-Meta: 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 qK2zZY87 i+WSf7LuGmYtRfxcejxl7QUYHQjW7PtC8InyTUnlx8lZgMkf8dsv59nN6Ztq8uiOM59CQXVqlv7jJWzxbwM8HoP56f92SQqxgAw/7G66hFVSrsf+t9bCTkdcjTKfkm1yLg88QuoNOgO85/drdq7sFt53izqMdYKrOwDiDTJWgAmfCqr36t2jicccFi9s2cYCWec8ETsugpnsLzvTPPJPfXXPm9RhsZYrcqrduy871TvN30+H4sGNZvl5zfKgJqpG86/WFc2KUtTwep5GO9s7SnXdDE2qiX5Y/CXuSlX8lf5jFu9hNrbOTia64XYsESfiQL/z05927Olcs1JA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Oct 01, 2026 at 02:07:40PM +0100, David Woodhouse wrote: > The *consumers* of this memory provider API will include KVM/guestmemfd > and IOMMUFD. The latter *might* be through masquerading as dmabuf, or > IOMMUFD might treat memory providers as a first class citizen and be > taught to consume them directly. If we are reinventing a dmabuf improved for these use cases then lets just use it directly. It would be nice if it could handle MMIO and "cachable MMIO" as well. Jason