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]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5F44C3DA7F for ; Mon, 5 Aug 2024 23:29:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 010756B007B; Mon, 5 Aug 2024 19:29:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F02E56B0082; Mon, 5 Aug 2024 19:29:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DCA0C6B0088; Mon, 5 Aug 2024 19:29:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id C3B396B007B for ; Mon, 5 Aug 2024 19:29:12 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 7989C407F8 for ; Mon, 5 Aug 2024 23:29:12 +0000 (UTC) X-FDA: 82419784944.13.19390D1 Received: from mail-qv1-f47.google.com (mail-qv1-f47.google.com [209.85.219.47]) by imf17.hostedemail.com (Postfix) with ESMTP id 8761A40025 for ; Mon, 5 Aug 2024 23:29:10 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=B6nseE+X; dmarc=none; spf=pass (imf17.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.219.47 as permitted sender) smtp.mailfrom=jgg@ziepe.ca ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1722900504; a=rsa-sha256; cv=none; b=458OgkllO5GBK925ErIpoXJV5UojMAswv+kkll/EJNJpUQ+0aSqQFPhRUieYHFRBe+zgwm DB/ZAFX6Y6iAVv9g4QuVnd/UHjW6Sp5xBU2XFhB0Ve8j8x3N3KmXNoMqfmaiivGlIDZTvB JURSD33FFBsTNUypdp7+zX9dI01sz1g= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=B6nseE+X; dmarc=none; spf=pass (imf17.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.219.47 as permitted sender) smtp.mailfrom=jgg@ziepe.ca ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1722900504; 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=Ud+vs2yn6sXlpWsYL0inF2KS4QwbN9S8Dxwgfx2J134=; b=FwO78wqa99G5/3MG2d5y5rXm+EcrLdwt41k1BxfUXl1HzfXwpF5hbmiD8qf+nKw08wQU2E a6RB2KkLu0yuth2m3sa42bSX/TAwg/JVJ7SXEr+bquILl51Rg2EWAEBX032GU3UuMjX5Ch cth3j7e5GwmKASGunwyG4XW5N22x9Zc= Received: by mail-qv1-f47.google.com with SMTP id 6a1803df08f44-6b7a0ef0dfcso483916d6.1 for ; Mon, 05 Aug 2024 16:29:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1722900549; x=1723505349; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=Ud+vs2yn6sXlpWsYL0inF2KS4QwbN9S8Dxwgfx2J134=; b=B6nseE+XaxckikEVpEi2GspbXbi7m6B4SXo5d5q9ySRQQ14ME5GbHuXvw5XpSt1RW2 8Au9br+IlXeq4RwZNeLpNrQqRzAynC4yxs6PUSmqm7bCZeqS5qFmbWEQDyXyyVvvDMdM Sa1rWjH75qUK9Lmie8YcdZh+rXBg0In29y9rlUwe1oz2xF5RfCnYBDcAS/ketgmHlLVN Jl/l3gzn1DYgnM/k7vFIAnl32CMuF06Pi1LrQ4zb/fTbj5kSL0k5kAff91l489rQEz+u 7IQRiVDtI4YreARLBIVP8PB0nevTkL8PqWTOA+XkdlZO5knvJH9LnrsSknywkTFarfcX QJOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722900549; x=1723505349; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Ud+vs2yn6sXlpWsYL0inF2KS4QwbN9S8Dxwgfx2J134=; b=B/tzYO47jZTWvmUlY+Zm/wVs+7dZxjhiOn0f3NoVMUSWOXEOcO/OTNamh/to6NQZa+ tbDh6BTnaWMIdptRznXcfu2em8bSErRQ46nF6euLlzAGhuoSFeB4Cg8EfQP/cDPaU+T0 9owOdZvOErfZcuKSZnlANyeTANcLfg6f/GpV6nx+M9e4Lxd/MyMudLCzxWW81s/C029Q ye5EOSpM4Yk0Ief+6kNQfJVwavHklsjlVXJdS/+TaEnEXoV2IRbwOIgukIpy4C1f+XMW q51hLVY+K1pZrw3zCD/bqHucX6LspS96Fqi/57BUnEdXD6CcLhMGE7QpZWo4R82iSwda OF7A== X-Forwarded-Encrypted: i=1; AJvYcCUJtEDi5b4kE/4Kx9iPeN/bzgaUbOuwtokqI1NbwMTcULHdAjghpigFcb9UkO6NLMpeLnE1A9OdMfSltS5Gwe2wGVs= X-Gm-Message-State: AOJu0YxfNW8I+wMLOn2mmOYED9w11SMJBWiVKsNSelYfem44EmzUaja/ gRUHK/Vy32H64yE0uD8xjSoW7ljRCkKh7PU0cU2z9KyC96IT5kNUhC//tPKSq+s= X-Google-Smtp-Source: AGHT+IEUqd6hIg9HDyEzlke8VzqWmU4TFD6nLDglYJ354O5s+08g370xcdmQz9qNHG00XmeufXnXGg== X-Received: by 2002:a0c:f209:0:b0:6bb:b478:52fd with SMTP id 6a1803df08f44-6bbb4785327mr1712666d6.31.1722900549464; Mon, 05 Aug 2024 16:29:09 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-68-80-239.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.80.239]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6bb9c83cc30sm39451646d6.101.2024.08.05.16.29.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Aug 2024 16:29:08 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1sb78W-00BvtY-0n; Mon, 05 Aug 2024 20:29:08 -0300 Date: Mon, 5 Aug 2024 20:29:08 -0300 From: Jason Gunthorpe To: Jan Kara Cc: James Gowans , linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Alexander Viro , Steve Sistare , Christian Brauner , Anthony Yznaga , Mike Rapoport , Andrew Morton , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Usama Arif , kvm@vger.kernel.org, Alexander Graf , David Woodhouse , Paul Durrant , Nicolas Saenz Julienne , Muchun Song Subject: Re: [PATCH 00/10] Introduce guestmemfs: persistent in-memory filesystem Message-ID: <20240805232908.GD676757@ziepe.ca> References: <20240805093245.889357-1-jgowans@amazon.com> <20240805200151.oja474ju4i32y5bj@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240805200151.oja474ju4i32y5bj@quack3> X-Rspamd-Queue-Id: 8761A40025 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 7zq4xsxaxo7j8d7nt8buzayrnsfhinns X-HE-Tag: 1722900550-562796 X-HE-Meta: U2FsdGVkX18GGebDfP+5/r2eFDg7LIOOqA+atUsepef5LzIkkA90wwDbRFjfsDydy6ts8U/ke4NtNNs+dkr6nv2AWG0VkbITyhxob31iLyQ0EUODQ8GFJSooNTGOTYu7sQhhkx5DdXnv0Ei5eB1LRAcs91a7yyRR+ege9BTLE2r3eB8KZtTS/SBwS1mMR/FY1g1rmr2l2xDvWkhV1Om4W63SdXaqszJQ/nZ9hc7dgHSQMf1q9dGzRhR2BQnyOjaF+aKUENO3FXx3/BPsPjEYWY3FIktwEMeN9y7x+TboUmClFISEnvkBX+YDwe4+cxN32oZxzaE/xyV4thAvUGMYXMiT5/QQYv6oQrhRHxOZi9mlclOBkDpp+hrEmpy6SkUCNU4ySBDjpRFUFPxrb9Vu0omxj6UfmHkyScSSpeuwNWT2NsixEBirBxPCEe4lfaH089COLqimtlBhKDbYsAQK9ms3jKOWTmVp3G1AfyarFDCG+rRgiAyukxYOpvFXJZUSlrbZ1L2PftERhxtQ1s5TysgVQ/JFsM+oT+UAvDqvr3wO4SBamQCX8kKlTXdI5RlZZlNZ2roHE96+EDCj2lYpBazGFfOE6aCMsjVv0kzXpE7hmev24OIK32RnjAxjbtc1uscUpY72WWWpuYkzok63RbwIASlvnFKXdAGM3oVNlFC9sBlrHI3+IC9orOM2cA7xGgyNxmvZ/G4F4rUQ7yLyhy3fomlA74eGCfB98m/LNrTNNXGuMRrc2Z+o6XD4tGnPIOZA6N9uEJUJI88eycG6pnBnOllp9eIPZRjgGHde0AxLTiUSDYS9LBCGFNeGJrn0Kcvh1qlz5TK69678XVdst+CFbMcO6i0/r1h/k1wAJVI+Fli4v8NiPK3FcWl4LKsSHPs8lk6ZI4vJynPTg4VvvS5em6uenKNhhBwUvxWy16zXXfbfnSmiA2DQ6+xiPut0d/D7SozoPeZkgpkZDNh m2z9qRgn jbCDyfiehSF9fxX+6jSDrDtTzAjAs37brs25KOZRNgJL1k6wy/NRiIpZwIYU15wvnzdFodPSQGjTJJPDhVJmq99XhdVNkHo/aQsm5PimddlgoTLB5Vh+y8nXqPB0/Z25wYybp5/iv8KS6lcm8yPZWjHYOkn57t3iSWn+09Bd0eDg/d1oOAEn2FBr0DH7Gn+h7j6VTlFfM0VCSeliZF1jzo2/Zz6AHCE69i90F2lSWzAJ33Aga7w/lvmt0xqyh10XUPuOGRuPIjksgf6w= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000103, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 05, 2024 at 10:01:51PM +0200, Jan Kara wrote: > > 4. Device assignment: being able to use guestmemfs memory for > > VFIO/iommufd mappings, and allow those mappings to survive and continue > > to be used across kexec. That's a fun one. Proposals for that will be very interesting! > To me the basic functionality resembles a lot hugetlbfs. Now I know very > little details about hugetlbfs so I've added relevant folks to CC. Have you > considered to extend hugetlbfs with the functionality you need (such as > preservation across kexec) instead of implementing completely new filesystem? In mm circles we've broadly been talking about splitting the "memory provider" part out of hugetlbfs into its own layer. This would include the carving out of kernel memory at boot and organizing it by page size to allow huge ptes. It would make alot of sense to have only one carve out mechanism, and several consumers - hugetlbfs, the new private guestmemfd, this thing, for example. Jason