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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 931E0C79FBF for ; Wed, 9 Sep 2026 11:25:19 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4hfz4Y4X1mz2yqT; Wed, 09 Sep 2026 21:25:17 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2600:3c04:e001:324:0:1991:8:25" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1788953117; cv=none; b=A83oKqyoxoCJEgGQ6syov3Mz5iZ8TDxkdnlQ2Ho3j9jZLUbZan1LcJsFmZkpp8OdoOaLVn2FFSW5Co/gtASDdtxdtM+b9Ha+a24xNzvVrUiHi2oZJjRgSwpk5u/qxcJvUKIuQK5XCmXm/5WTrshLTSHAgbZDxumw9HttTV0q4sDMH9ojCPP/fmMA0e1xEKSs6IgABgX9WhMuPfdX1jLxUdi9z5DgnntTXCmV2Fa+sKw74M1NKvYXzZn45EcRmYJW8KLrM/oti9vgobRtWfMtrewUeoOrD3JL9iiG/ULOqkY15Ak6IbHjg7bRKu6iHACugHCf+RA/2VRy83EdMlLdPg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1788953117; c=relaxed/relaxed; bh=inNJzZhlDskfV4tobMRa6NUvX+KktI2JxAaJsuypEcU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CbUQAwdre9iAqotwWd7xh7Ccag5XZOxV5jQ2wPcr71/O6uHHbcaiLklUtskV+gv2msVVBY//FB5T1BJoxqHVgBCDW23KTFqy8aImtb7rgigCcWpbZ5VsBSb84HyoupSNP27+V1OvJb4NReXpB30+k7uJYE4WdVkbaW6hdxFqGqlzc2DRQwwmvguZBOk2QKqrimlVUY8YI5lngc1FOTjwqXnMTNK0u0l479JmZXLlUi8BDImWyuIKY3b9O4GSqduqDn+IGXWLWLjsYhdlXk/A3iJgZ3Y9oZqab8g0TqDPG86KtY47N9boVZpwkQuEn8m5Lc1bDJVJRHjUgoPW8uMg8g== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=YCsVcikz; dkim-atps=neutral; spf=pass (client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=ljs@kernel.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=YCsVcikz; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=ljs@kernel.org; receiver=lists.ozlabs.org) Received: from tor.source.kernel.org (tor.source.kernel.org [IPv6:2600:3c04:e001:324:0:1991:8:25]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4hfz4X2zZbz2ypw for ; Wed, 09 Sep 2026 21:25:16 +1000 (AEST) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 08BF160211; Wed, 9 Sep 2026 11:25:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA8571F00A3D; Wed, 9 Sep 2026 11:24:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788953112; bh=inNJzZhlDskfV4tobMRa6NUvX+KktI2JxAaJsuypEcU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=YCsVcikzxNnvBT0Y3c5qUMcZq6CnjiF9LAucMz9KUDz/X8rycnl20TJiMBuTV44C6 ciuJ5X0Mary0o+RdhTl8tWHSISMo1lGTn+IXwhIQfs7dZg1NC//UvrgDFVVFH2BXXg wGSvIxQ/NBgeVTkoO77PEhxG5tF/kt0hk770YdbvA7jzYldeFCi6gaAA3Ie47dGZ4o rDioSU8ROD/U0Ex4wV585kl0B6XRkVhfL48+PBTUa/l0vXguhxnOvt9I9np0ualYy6 L7k5zESC+bnaJX5hWbMNkzgmSv0XEtgXO0Eiy5hQl/cIt/eJwNjq2z/FZB7YFfjxHL 0pO6lgM9ge/7g== Date: Wed, 9 Sep 2026 12:24:48 +0100 From: "Lorenzo Stoakes (ARM)" To: Andrew Morton Cc: David Hildenbrand , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , 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 v2 00/12] mm: make userland page table freeing RCU-safe Message-ID: References: <20260908-rcu-pagetable-freeing-v2-0-1f60b64e878e@kernel.org> <20260908141543.8180b60400d38b70d249949b@linux-foundation.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260908141543.8180b60400d38b70d249949b@linux-foundation.org> On Tue, Sep 08, 2026 at 02:15:43PM -0700, Andrew Morton wrote: > On Tue, 08 Sep 2026 13:32:09 +0100 "Lorenzo Stoakes (ARM)" wrote: > > > The majority of architectures in the kernel defer page table freeing until > > an RCU grace period has elapsed, this series converts all remaining > > architectures to do so too and eliminates CONFIG_MMU_GATHER_RCU_TABLE_FREE > > altogether. > > > > This is important because it enables safe lockless page table walking under > > RCU alone. > > > > Doing so allows for reduced lock contention, avoids lock ordering concerns > > and enables fast, efficient and correct page table walking as a result. > > > > Additionally it removes a bunch of code and architecture-specific behaviour > > which is always a beneficial thing to do. > > Thanks. It's early and unreviewed, but this is mainly an > if-it-compiles-its-good thing, so I'll add it for exposure to the > build/checker universe. Yeah largely, and I have done additional testing for cases which need it. > > > However some arches required extra attention - sh-X2, m68k-motorola and > > sparc32. > > OK. Please lmk later if you think additional reviewer/tester attention > is desirable in these areas. Only really the fancier sparc32 setup which can't be emulated [there's a call out in the cover for that one!] :) though sashiko found an issue with that that is now fixed. The other two I boot tested locally under emulation with no issues :) > -- Cheers, Lorenzo