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 835DD47142A; Tue, 8 Sep 2026 21:15:47 +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=1788902149; cv=none; b=ek1TGR33pUB7SYyguri/IAehunStxepYD9RhAMNoGBaUbW7W7stGGj6epvA7HXURc9IpWjBLqxByFF92TvVVWLgrmX5ei3KT6J+6xOrjKUlfuuziQEhr75eAzjDr58q4jjpXG6LkKiYZc8A0nRBm0Tj4gXtd59+4+/++nNaUks0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788902149; c=relaxed/simple; bh=zc0dRxXkAKZOT6fy9WXzVz+99ipKkrk9hWcPiEzdJAA=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=mCY7PWkUvP8KLIrcBlbWX34hx1AtDxKaheICrOpuYAM9k5mS9VUkn51BV84CWDhJzXQymStDdvsGMkfjTPVV/P/sG+PUKTODywU0iRIi4zmQqDZU11aIZL0Q09mdfFFvwW4RoWUg9Ud6/z87UInG0WJ8dHpJncb9AdJ40Hha47A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=S61FQutZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="S61FQutZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E1EB1F00A3A; Tue, 8 Sep 2026 21:15:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1788902147; bh=eVg9GefJyoXHHA5a69mXqnQLyloUJ4YxIPGGpLvgyr0=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=S61FQutZ9GAkmusTuBm8tba1mRd5os9NdWI1OcYUdnUCilKfQqRFUpY9X0910S1CM WZ7yUO067yRvIkgkaa3uP271RNhAevtq90hMdQ5fuv0628aYooJ26Y2LotuEU39MiY QQuRFXCkF1Dzu+58mWFPPcGHJySDbzaovnewoTOY= Date: Tue, 8 Sep 2026 14:15:43 -0700 From: Andrew Morton To: "Lorenzo Stoakes (ARM)" 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: <20260908141543.8180b60400d38b70d249949b@linux-foundation.org> In-Reply-To: <20260908-rcu-pagetable-freeing-v2-0-1f60b64e878e@kernel.org> References: <20260908-rcu-pagetable-freeing-v2-0-1f60b64e878e@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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. > 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.