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 15F84D2D0EB for ; Tue, 13 Jan 2026 14:46:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 13D6A6B0005; Tue, 13 Jan 2026 09:46:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 115226B0089; Tue, 13 Jan 2026 09:46:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 04B636B008C; Tue, 13 Jan 2026 09:46:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id E46366B0005 for ; Tue, 13 Jan 2026 09:46:11 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id A56D7B5CA2 for ; Tue, 13 Jan 2026 14:46:11 +0000 (UTC) X-FDA: 84327215742.26.5DB1937 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf18.hostedemail.com (Postfix) with ESMTP id 104DD1C0010 for ; Tue, 13 Jan 2026 14:46:09 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DWF2snKT; spf=pass (imf18.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768315570; 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=jSy7jBvC9nebYOjTwgO9FutvaOd0nj9PGpV6sjReCbI=; b=J6AehDJ1QV7aARcwFyJjCOoAeliLZiXnng+4xbVlsl3CduFzAK36AcWnsO+J+EZinC3Qqx pycF9qiEVzMgva9YKcJmsretn7QF9iXnSifQ2qBM7drzdCUtn6VanROflP6443Ty7BdaWT Q/nskhQkcaquveedAJLfrvnhWZCy0bA= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DWF2snKT; spf=pass (imf18.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1768315570; a=rsa-sha256; cv=none; b=Pp8B+ssVpbHv8rfLUJv8cYTyMyXYdLJG2cWURHWFm54Jkjhb3a9VHrjqXHGYBJqL8Rqh7C IYkOG1gAZ3GQzC9hUACw9S+auH8jmDVo8yBesckQoohx0oCd6mKtaMi3uYIcziiRLlYaRi UUJMaKoxLn2tiZj9yAsvh2WT7GCSBsw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 211EE6001D; Tue, 13 Jan 2026 14:46:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A77F2C116C6; Tue, 13 Jan 2026 14:46:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768315568; bh=4uCAucSurgWYYIfTPVGMA7hAEuKLq8ADMBBO1vAY/Ts=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DWF2snKTTWME68p5bqRoDMZp5nz+HXJ3bikIf6obk6LehQbfcBB89unOKo0echBdQ FuaLneguObpC5wzEdpQ4rXKS7R+Ve5bjzkv3OLAU9ULW88251bOBr6hU6ADJ4kju8g Ow6/uz65FMFNWthx0KS95LsdmFZZ89cakQFpXsZjmBoc6LAFAoBEQ9+wOqAOQ4UcHj 5J6wu98pb1caihXnGjUDkQ6+uXeDHWR1nEAKf56OwSj6TZZTGkxmse0ttEsihnjDqj 6MjG+RmsooY9V3L2ZPU8Fj55ZhiqPZ64NpuhkDFoZhEoO57LJvo6aI93ajbvqAI/OW 5jmKNED0nhbOw== Date: Tue, 13 Jan 2026 16:46:01 +0200 From: Mike Rapoport To: Jason Gunthorpe Cc: Jason Miu , Alexander Graf , Andrew Morton , Baoquan He , Changyuan Lyu , David Matlack , David Rientjes , Pasha Tatashin , Pratyush Yadav , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 1/2] kho: Adopt radix tree for preserved memory tracking Message-ID: References: <20260109001127.2596222-1-jasonmiu@google.com> <20260109001127.2596222-2-jasonmiu@google.com> <20260112143904.GA812923@nvidia.com> <20260113130526.GE812923@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260113130526.GE812923@nvidia.com> X-Rspamd-Queue-Id: 104DD1C0010 X-Stat-Signature: 67spueho97ty6y9b3u3ad8caexkqyxpm X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1768315569-408821 X-HE-Meta: U2FsdGVkX197AHTfq/6lWz/j9A9r/EFt6oqq8HNDAtAicv0aagcfyErW511KdDQGxCx6W7GjUAYnBAgMVXOUNwmrGBciLugDcup1XS+C/xC8ABWfJSgUA0U/YFj8mDDmkoJjORkWx1UFOQLw+KXO6S3271RIgPNxiuD0fdTWxmgHAGo95VL8Jl3R+1RaLgTRGXzgZuSu0UOrdrdtlIQ7PSas3zbBk5rjlZuhEtYlNEVFeVJDe48Rh7EaiJL01YY2h6Zr1Ry6WfPBbYNOjtu6q/o7Ph7A6G4H79HlPFiba1j1lIjjOCPxi4nuFnsrBb/g+FtNSrKC3Fta+qm1cLBNyBSc9TyLxSCVXB15eEMEVc6lzLYbW/+lnuMtrkAvefCNjTROltk8G4mIVTGy3eWEj0Kk0Pv5qBjIdsFDZAfTmSQgI3YdrmHb5EpnOXakC8N6MKK0lkMrJ3BLwmGO0sv2k/9I6bONs1+CPPqik6nJ6bTLxwKxcwb0RkQAwS3p2MdBlFq7Ld8j0AlOjDLDslmDIBHnd6APKcjDyJhEBBr58MZZIRGZYsSDJXPbgjW95GsSglJurZatXxhta8YpH9oc2JvUO5fvwMc5Bh7/8HVrNMqHYMeTlj7kXOnfLZLX10woNYH51kIihbMd7aKLUbg3ZKgkNx1mohJr8gC0Bf+66SFSvi5ob/ynhfIKzVTMCocK4JYpkAYwXrOYfB/De7uuGrFlPABWW5zO+tMQTwmJAyWfXoprENIDph75FeNgzo7wgobmMKRlHGhXGgy4t5ZE8BQtJdr6Chx+X1bq9QHBR7NjM5m1+x8GaZbc9GVeVgoVrO0BseRshtLytXhfXKZ75CZWdfrhBjoC6oT4KuijYtDuFsYOYskne8jS9f6hH6+rM9oDA9cxVcYByUd6rOMOxeKZiIZ0m+GXuqumhVBER1J9+u6lWalkJN5vEhWwCjg8mI6NhWDB3ky/sT8/nCt F+69mFiV XY9Rxli9LxCbIqLZ8hE8H8HcRCneA2g2BC1+lypMOHgaTZMRvnDrZcgiHAuA6jfCDPZ52N0guiUMpfGy0PnUw5lH/Ez9OVazr2DjlNK0KjvONccZjDCNfk44lFBmIkv3ta3+oXKTIZQNqdzb6qUhRaxP02mFKPGAou/3rlG/8Yuwo4uiuxL6gChDEk60qANVaCtXCiu7X4J8Va9X4HiMemBZiG5mCeMsSMKtT6Y/JGNvmoo0+L3irsqYRNOo8cCsqC0G8 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: List-Subscribe: List-Unsubscribe: On Tue, Jan 13, 2026 at 09:05:26AM -0400, Jason Gunthorpe wrote: > On Tue, Jan 13, 2026 at 01:34:42PM +0200, Mike Rapoport wrote: > > > For example mshv intends to use kho_radix_tree to track the hypervisor > > memory and there unpreserving will be a part of the normal flow. > > I do not think this is a good idea. Sorry I wasn't clear, mshv is not going to use KHO memory tracker but another instance of kho_radix_tree data structure. I don't see a problem with that. > Nothing should be touching KHO until a kexec sequence is started. KHO > calls should WARN_ON prior to this point. If a kexec sequence aborts > then the entire radix tree should be discarded and it should go back > to WARN_ON'ing KHO calls. The whole point of making KHO stateless was to decouple it from kexec sequence and let userspace control when preservation happens and to allow preserving as much as possible ahead of time to save cycles at kexec-reboot. > Jason -- Sincerely yours, Mike.