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 17F38C624D7 for ; Tue, 1 Sep 2026 14:04:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E3D5D6B00CA; Tue, 1 Sep 2026 10:04:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DEF506B00D0; Tue, 1 Sep 2026 10:04:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CDDE46B00D5; Tue, 1 Sep 2026 10:04:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id A189F6B00CA for ; Tue, 1 Sep 2026 10:04:01 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 10B301C1F3C for ; Tue, 1 Sep 2026 14:04:01 +0000 (UTC) X-FDA: 85165362282.27.3F4DC0F Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf23.hostedemail.com (Postfix) with ESMTP id 636AE140014 for ; Tue, 1 Sep 2026 14:03:59 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=VkHIyhIL; spf=pass (imf23.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@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=1788271439; 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=utZgOAk3glT+w9jGyIL1e4+wDW3VgIywx5aDJ+IClBI=; b=cAk/mXiCCrXyQKXxIinXHIS23BR+Upllmk4HOcJbZ0v3kihabKxtE2kxF90fzrLzVc2bat NeZKNlHqh/PsvdgyUwJcuAFeFPTTgOM65+d9Jo0R6Dtx9UrRzSXkGMA4a53sfQB/Ch5GU0 vVT/H8HPnqXDxlKwawBicZ2PGqTz4+4= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788271439; b=fEly9ITW9fne8ObfU2KRIbt04p1PsIJyeJLbCBVDQMLldIR7/l1phV+3sXP8qNr2qKSEOG 8qTAEYralhMgGCH+m33mBpiiLi44oRESAQASccfnwg9e92lFbZ7JpCKnPMvqQsX6OgJ3fV IZzTZDDRBOb122h9aAeoyk65N/lqeJ8= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=VkHIyhIL; spf=pass (imf23.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 9425B60214; Tue, 1 Sep 2026 14:03:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9601A1F00A3E; Tue, 1 Sep 2026 14:03:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788271438; bh=utZgOAk3glT+w9jGyIL1e4+wDW3VgIywx5aDJ+IClBI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=VkHIyhIL5RYsevDjObNKXZqn+SdY5WQb69y59u2HEPU8+koXsjF39lkchtgGfID2/ RRta8sEiyqrYHeGZADgvcepo/d6BCIy1rew63LXlaVY0Xupe7DXsdoMNSJ2LwTdz2t 9L5dRACEK20PlxkRCThhZUhUvCQOFVCbvgosbtCrmvTH2mK9HkGA5IIhEFa7R3t6KR sYprPzYjwJdozsniM15JaMhNn3suHrmHgExLHHHmoISXD5OQ3cY25wcuADGpitpChH /n/kgOyZ1a5axdohia++5dysGbeDD/F5NBdm+JhIfjt3j2SloNQlLySaTEevH9y1p5 qVSTayD4zeHWQ== Date: Tue, 1 Sep 2026 15:03:34 +0100 From: "Lorenzo Stoakes (ARM)" To: Kiryl Shutsemau Cc: Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Guo Ren , Brian Cain , Geert Uytterhoeven , Dinh Nguyen , Simon Schuster , Jonas Bonn , Stefan Kristiansson , Stafford Horne , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Russell King , Vineet Gupta , Michal Simek , Chris Zankel , Max Filippov , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , "David S. Miller" , Andreas Larsson , Richard Henderson , Matt Turner , Magnus Lindholm , Catalin Marinas , Mark Rutland , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Madhavan Srinivasan , Michael Ellerman , "Christophe Leroy (CS GROUP)" , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Richard Weinberger , Anton Ivanov , Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Arnd Bergmann , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , John Hubbard , Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-snps-arc@lists.infradead.org, linux-arch@vger.kernel.org, sparclinux@vger.kernel.org, linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, Hugh Dickins , Qi Zheng Subject: Re: [PATCH 11/12] mm: make userland page table freeing RCU-safe Message-ID: References: <20260901-rcu-pagetable-freeing-v1-0-5456a81c8212@kernel.org> <20260901-rcu-pagetable-freeing-v1-11-5456a81c8212@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 636AE140014 X-Stat-Signature: 6qaxxwo4nhch31fsetz44snx1cpy1jao X-HE-Tag: 1788271439-668889 X-HE-Meta: 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 WRbY5bZf BUTeXe+KfKIzKs1KIqjJxqnQavsvZ+Snd4O4tnWl2wt8lxmX2W0xeYLyneEUq+o2X0vcROrP8JJjLbOTzeA5N2q+tmIMP4cPSPmdDAUEtucqnNDfiWCDqqF62zCwxiFI1fW5QK6mAGinLQa9i95vWwXqU3vqMoxuhvAC31vrE0OqhuOZ5IqhWr+T/qD3Z3x/IUb5zyddVYwTXqea5Uf/FTjs6MnoNloMvkE9rQ+LVluBEJcCkkxEmrroyDhBPj3XZoDj+KszrHYBzbXMcL3txAjaKQtYAjFenY01V1lvlDjzfc6DOElfMeWIfadV7teG0O6tk0Kdggzd3N2k= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 01, 2026 at 02:33:14PM +0100, Kiryl Shutsemau wrote: > On Tue, Sep 01, 2026 at 12:01:31PM +0100, Lorenzo Stoakes (ARM) wrote: > > With this change in place the kernel policy is now that all page tables are > > s/all/userspace/ as subject implies? Right yeah :) I hoped that the summary line would clarify that but can edit that also. > > BTW, what is your take on kernel page tables? Do we want the same policy > there. pagetable_free_kernel() is not RCU-safe as it is. Yeah I think so too. I may follow up with a series to that effect also! > > > freed after an RCU grace period, and thus it is now safe to unconditionally > > perform page table walks under RCU, safe in the knowledge that page tables > > will not be freed underneath the walker. > > -- > Kiryl Shutsemau / Kirill A. Shutemov -- Cheers, Lorenzo