From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3CFB237E5D8; Tue, 1 Sep 2026 13:33:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788269620; cv=none; b=mpV7BCQFcgpcvb/LRHYUgl9RJyr6urEOd44UEgyc2EfLiR/G6XsvZPTkrZS4QsoyiHufA0E+Os0QZ7+ZgRFR3U26tccfnnNrozxk5kn1o3JHK4TTOtFFava9H3luwxFcWqPgCcWViWlwmBXcq2VSz3+IpMa1M4qPRSBo0XlJn8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788269620; c=relaxed/simple; bh=L8mffahwowpqu6th6laYccc721TU8H9CSNOMIhSy280=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FcAB4+cnEBbj0sspr64CU7s5kdYcGx3uubQiXWH8/AkAmXJTFwwKJT/FndjE6Z/t4KlCRHeafAx/qwBUX6X/BE6+4jxBA691C/8kSKmPTVaPvrOKQbCzetdv6cBdgdDv2Z4n+lo6WQdi+IiXgyfokYovBfpyHhV0laAB85AiKPs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EhPUjdjb; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EhPUjdjb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E7D61F00A3D; Tue, 1 Sep 2026 13:33:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788269619; bh=jcbNqyZ4CJOFUcx+fZWWPKksNhyQwz/xPjmgvkWytSE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=EhPUjdjbePHeKrlhJaT/qdk8eCghU/xkjFLX2ZSOrSJgzGKxnfymBRLvRLIAB+lil LtyBPDuXQdS+62s8eoQup2ev8Bz3o3XBhF4l4zD/nMnmup/sePSt7atgjkAu6O47mQ f2pkabp2vmMejJeXGz6/yuYsn3G6A/J1getiSJCPN/ClVN7b9CEtMwGWDPDP0Lx5KX KDSEashxYtrPeaO0yRDcNqCrSU92Y7B6PwssrqM9VvmutoLso969XjnVariqlE82JI M0UCUlJLZx9XB2ca5ppcTYmrYgGfMIeWQa7fJQmKFlwQewkP2LNLsro6qKNlMDG7ry DkQIRfv8jHEFA== Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.ams.internal (Postfix) with ESMTP id 57E291980064; Tue, 1 Sep 2026 09:33:18 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-02.internal (MEProxy); Tue, 01 Sep 2026 09:33:33 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTE7XYI88DUY2gRkJOK6+ZyCIFoNn8bzP7pT6CkwBKHBvKWUe6kvcLZyJKqoR/mFua tnuce/0i36y0TC7Im4WvZyoy/crD2rPu16GAU43MkToFESYNa+q/dgDmYeFoLAKy++6ZgW 8jn2vUxLTK4d+JU7NpIMhvmFWN+lBL6CrhfWBNMDXcQ2eFN5VMfwvgG7wpe8357MD3J5gK 7xFBRFrqPTsz4yMLY+EEChvmjl1qNNrFzTmc4wdkVOaUc1KRt3nz4X6b9lgB4AP7QFsDWQ tYyrUQvI3wO8SrGFb+1aGvYLJgVsklk3Kc0+LAmLAEM6pSFrAQvRZGfFtBIFEXt5smoDZ8 0sIIODp3p+XbaMM1IQmfCvE2+2bbjw/rRlbPqyxvx3AWjW0wx69YF5Ocr+JktO0nTZOok2 HEw0ft0H3myd2V1s6FmW7lpkinX5D+jdOQrkC/osJIL3mBMTcjL7XfwqTbI8tt3mank0qt BcT630GiS2PTitGfmJ6/iVLTorQObFhmiWUpu/4o8m4w+lLom0XGtnouU3SvS4FcugWWNZ 7nEECz0GGK+6YbBSmEMxBhw/vyLb4HqtpoQS+cM14FfTsm1gjY737Jmi4qjcP7ghw4NaMo mSjmk0LJqLELQl49SSqDTw86/FRQj/i6o2/Z7vFbf6wnUbIU1mKMMzFy+Xyw X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 1 Sep 2026 09:33:15 -0400 (EDT) Date: Tue, 1 Sep 2026 14:33:14 +0100 From: Kiryl Shutsemau To: "Lorenzo Stoakes (ARM)" 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> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260901-rcu-pagetable-freeing-v1-11-5456a81c8212@kernel.org> 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? 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. > 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