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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A1A47C61DD3 for ; Tue, 1 Sep 2026 14:04:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=utZgOAk3glT+w9jGyIL1e4+wDW3VgIywx5aDJ+IClBI=; b=20qzymUzlZ3yha2hsp0Pq4HK3K WNu/vRsMcWNhD+Ok+aZRclapmpN0OERXPLAlN1PaUh+Pb19ARoLFuZiLc+ItCB5tfnGYydc3YjTXs SCr71OyJnmu+NRj7rKm2WqPuSxUxVcNW+aEascRPVXoG8D9MrmOWtO6s7gMid53IScCo4rfqx9nZe 1z6Y7unsW5v2EE9IIS9ZmWQHeVt+dIUAiTIgtCXxBRl8+8VETCxhpESWAezlsTphjtiSZQtIL5gqN hQ4N/myIChA2z0h93+OWLF0CjLy6iD4cdtT++Ldaf2lzEQf5eMQhh7y9uqKNznB3S9WHSjj+bdQZa FplgBm5g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x1P5m-0000000CH3s-0Byr; Tue, 01 Sep 2026 14:04:02 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x1P5j-0000000CH1o-2aZ5; Tue, 01 Sep 2026 14:03:59 +0000 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-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org 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