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 0D1E7542817; Wed, 9 Sep 2026 11:25:12 +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=1788953114; cv=none; b=lIAb2VHJqwMVcS9uQqFChkwedFHxHgrF6H+72xhdQ22dRy+sdq5O486RXEfh089hKuCc9K84dPMWd8WXSBR5L2ws7gYsv5INlDm2UjEUfD4LbJ9ChjebglPFSql+BIK+J2anDyMhyhUattYBUVGe4McV6ylNWysRoXqt0aMTu3E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788953114; c=relaxed/simple; bh=k9Nd2U2iPKPwFxgxgN1zBGer8nrowwuMplrTHjGrDOY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DBRPn1W93XkERiVCXwtD+L1zrBJNP19eeVRvoU/2EiNDRFfgsybvrg9FCTzrYPRsP+89cfmUpjJWTALmDzHo/IgdY1Ndvg3ILntAkz6yFU1YYYzO9wsGjhddICcKZ4aeUnFGsIEYqwzzMFNO46Z4vuckQiTGPgIyZuWw+QGUGTo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YCsVcikz; 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="YCsVcikz" 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> 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-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