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 5F3CAD39008 for ; Wed, 14 Jan 2026 19:02:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C5ED36B008C; Wed, 14 Jan 2026 14:02:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C0C426B0092; Wed, 14 Jan 2026 14:02:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B361D6B0093; Wed, 14 Jan 2026 14:02:49 -0500 (EST) 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 A23156B008C for ; Wed, 14 Jan 2026 14:02:49 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 3336713B5F4 for ; Wed, 14 Jan 2026 19:02:49 +0000 (UTC) X-FDA: 84331491258.30.597AC0E Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf16.hostedemail.com (Postfix) with ESMTP id A1E64180012 for ; Wed, 14 Jan 2026 19:02:47 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MDy3xT6j; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf16.hostedemail.com: domain of pratyush@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=pratyush@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1768417367; a=rsa-sha256; cv=none; b=XkOhxubeaLugqttjvN97BrJv8QXwWOWxp411rPs2bs07WYTVZfQRm6NZoI+Do/mOsnTt2y 2QfiSN/NyjMA4/9mtry9IgLTBbleyfRqhrUqFmL9Zi0HCQgG/jF9Ge3Lr68t34nyNVod3P yummDDnq6eLhtN1SJF/eqyMJt6v+PfY= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MDy3xT6j; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf16.hostedemail.com: domain of pratyush@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=pratyush@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1768417367; 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=K6LZNNkSxE9Tb9HUp9nc6tRbG87lkfFbOQymF4sZ0mc=; b=NEVmMwVHfruEcPM4SPC/DpFVUxxD6ETNB+6oHaAQ//0cFH3nhq90RKAREw07NRJi1OjnpY 6M1Coj7PEYo5f+dmkexvIImTv9RENhW3WtwGNq0BXZkmj08peMHmnpXT66MbPg/056fyG8 avty4j6zfjQHtu33QznizJIUuFaJjuQ= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id CA04E60138; Wed, 14 Jan 2026 19:02:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AC1CC4CEF7; Wed, 14 Jan 2026 19:02:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768417366; bh=/g7znYFrTNdvW4RKWutiVFghMR5mmCYvmvOEw8ACiRY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=MDy3xT6jPzV3ToLQ0kmCeUKluxH6b6eqZef89YSDaEdyPmUTF25s0ngTuJRsFWG9I 926T/0gY2RTddhgU1TCiaRmd4sCjIUiNFcQZzygn8PStwkaslCSJiBbriS+MdR5RTj B/PYWWzg6p+l/Y98krWhmMK6Cvrgw3f+JfcZjWNbQbYOpPZCIpFUDsjnIux2zFOsUM qS7dO+juVkXHGmH+RbP66XAuWNKf+qL0xFihgSLD8kYJp9N3hKv0AHG50sCTOIyUas 4CvfudY0fUeQnlrTe8OQZdiqGrDg83Wff11I/f/gUsKjJYUJf9t8TrQqO0WQYrdSdM CP8ErjTmVxEUw== From: Pratyush Yadav To: Jason Gunthorpe Cc: Pasha Tatashin , pratyush@kernel.org, jasonmiu@google.com, graf@amazon.com, rppt@kernel.org, dmatlack@google.com, rientjes@google.com, corbet@lwn.net, rdunlap@infradead.org, ilpo.jarvinen@linux.intel.com, kanie@linux.alibaba.com, ojeda@kernel.org, aliceryhl@google.com, masahiroy@kernel.org, akpm@linux-foundation.org, tj@kernel.org, yoann.congal@smile.fr, mmaurer@google.com, roman.gushchin@linux.dev, chenridong@huawei.com, axboe@kernel.dk, mark.rutland@arm.com, jannh@google.com, vincent.guittot@linaro.org, hannes@cmpxchg.org, dan.j.williams@intel.com, david@redhat.com, joel.granados@kernel.org, rostedt@goodmis.org, anna.schumaker@oracle.com, song@kernel.org, linux@weissschuh.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, gregkh@linuxfoundation.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, dakr@kernel.org, bartosz.golaszewski@linaro.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, yesanishhere@gmail.com, Jonathan.Cameron@huawei.com, quic_zijuhu@quicinc.com, aleksander.lobakin@intel.com, ira.weiny@intel.com, andriy.shevchenko@linux.intel.com, leon@kernel.org, lukas@wunner.de, bhelgaas@google.com, wagi@kernel.org, djeffery@redhat.com, stuart.w.hayes@gmail.com, lennart@poettering.net, brauner@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, saeedm@nvidia.com, ajayachandra@nvidia.com, parav@nvidia.com, leonro@nvidia.com, witu@nvidia.com, hughd@google.com, skhawaja@google.com, chrisl@kernel.org Subject: Re: [PATCH v8 14/18] mm: memfd_luo: allow preserving memfd In-Reply-To: <20260107185414.GG293394@nvidia.com> (Jason Gunthorpe's message of "Wed, 7 Jan 2026 14:54:14 -0400") References: <20251125165850.3389713-1-pasha.tatashin@soleen.com> <20251125165850.3389713-15-pasha.tatashin@soleen.com> <20260107185414.GG293394@nvidia.com> Date: Wed, 14 Jan 2026 19:02:34 +0000 Message-ID: <2vxzecnshvat.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: A1E64180012 X-Stat-Signature: bqdp7w3oeby34ccg6g9esijjz5nh4ipx X-Rspam-User: X-HE-Tag: 1768417367-808447 X-HE-Meta: U2FsdGVkX1+IyZg1dgXu1lMqpIJtBnvuWY1ja8VHwkr13oT31MFJvcqNsOLSwQD+X/jIrUeJXBb2Lx1/ARv3clDuRQC4cHHegPC4aVcML8szO+SgZsYCBWtpVjnY+WqcSUl5m/9jdxMUfiU6SSybECKH6mEk0PMbk6dvoeYxifSQEFQK7WxTW3G1NRryuQWL89mg9jFFn9bOijvSh7lW6cjJksEZAq3xte5m6tiI9kob7VQPRX9wG1hC4ad/50cL3kmIEobbZi7eD8omYX8BuJT91jFA79342qJOsVwE0w0nCowME/YjfF14O0bRdrbh4HnxP1TBD18AumACnDg97pZiZJFW5tCIGQT1UckLCmtyIHdya1yXcZFGtkV8D08lKZGagYubrLrbYfXFIz1/B92JCfZoS7cfUtuIRxBn9xGloIJvXSNjQGGqMZXUZxbYu8Jw3rKEV7aEFTXzkOgAqN3OSt3fhoimyz7RGYNYfWXVZxZ00i8L+CltqXnUQdXfQgDN1xuv7xKvUyNxvgAT6WAKmc8OMAgRM66kPEX3JVr9bh9e1nx77vg6dxeagpWTCyA25cu7Exq7EJk0+WhZtatFF6axChz0Uwa6GrUx2BtbnkHCnB+PAGmWiRiVB/u+g2hFYn0AhDJYTBVnL915OhChf0uO0MZE44OYYkk9+DIn1BC1treqA3LpZviD7TEZ/xAkr8ZpI+3d5S2wxe5kk8dC52bqNqSmfy9WrRZXrHp8XsUEmoRmXbTXRsslI98GzUWMIKh8nVBezDu+4ExALrGEvGwbZ/B93P+241cf4SGWG4rc4Cnt/lt121zZIMItSxRS6bDUsQdeT9VzyVLFaZfm9zGrSRHTqz1qfFV9P+edAxxSIrdysMSKpmI5SUF+/lkQT89mWADBnDREKjg2YZKrkzRtje86waNjUJkRjt/rEjgVjqBF+6TQHhP87wDyIPkABmL74D/9D5X0al/ rBGVjHit ZydhTXPHcXGn0oBobI4CnWBQXtK82GPkh150PNC3YzPjS9JbQ3xpLklSQXX/fqLacDtYu8ms529YTqQdEPr8WIlRgHCyGnpruceL2K0ykxjGQnjt0uRQaxulPQ+1GIeJFcKiBEzRT2+7ZhJKhPJvT+TyETKGuzJV7Wr9dh7Zgig+PKj5vrd3fqbeali3yzNPw8qbOpEEqqKXeH2XvdlYkllXz2iVdkxrVV1E+usjlHXkjT6xdoC9QqKwLoLG1CrbadcmrFwEeWg06C8sQVoQBMHROsd9pQ9u00bRgIFAE2hHbAkQyYv2BlgQxWQ== 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 Wed, Jan 07 2026, Jason Gunthorpe wrote: > On Tue, Nov 25, 2025 at 11:58:44AM -0500, Pasha Tatashin wrote: >> From: Pratyush Yadav >> >> The ability to preserve a memfd allows userspace to use KHO and LUO to >> transfer its memory contents to the next kernel. This is useful in many >> ways. For one, it can be used with IOMMUFD as the backing store for >> IOMMU page tables. Preserving IOMMUFD is essential for performing a >> hypervisor live update with passthrough devices. memfd support provides >> the first building block for making that possible. > > I would lead with the use of memfd to back the guest memory pages for > use with KVM :) I would assume using 1G-page-backed memfd is the more common use case, and this patch doesn't come with 1G page support. Anyway, the patch is now already applied so we can't go back and fix the commit message... -- Regards, Pratyush Yadav