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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 68D6AC98304 for ; Tue, 22 Sep 2026 23:00:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 00A866B0088; Tue, 22 Sep 2026 19:00:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EFDCC6B008A; Tue, 22 Sep 2026 19:00:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DEE146B008C; Tue, 22 Sep 2026 19:00:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B42F96B0088 for ; Tue, 22 Sep 2026 19:00:28 -0400 (EDT) Received: from smtpin11.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 415E88036B for ; Tue, 22 Sep 2026 23:00:28 +0000 (UTC) X-FDA: 85242918936.11.CB4E114 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf08.hostedemail.com (Postfix) with ESMTP id 5D186160005 for ; Tue, 22 Sep 2026 23:00:26 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=f4enYMEQ; dmarc=none; spf=pass (imf08.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790118026; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=67Wnb1WqUtfvvqvCH5gthEhN54uXfj3OJmtQ8451vqc=; b=g7Yajxqg3dwSMrWqhw4xsjxqxRG6q/uSOjSZZcgXDZr/XZ974wYSSPgz4LzkeXK0pei1Y6 nlbHPwObm0rbv4b8FDZhcPKD0DC9cU5AeYm+SReyw88/fg4WjiKHAKxgk86VUwVknvvMPm H4vz5XGuRck2hDTXjDommdGZrOy6PPU= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=f4enYMEQ; dmarc=none; spf=pass (imf08.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790118026; b=hSATWxt/8eaZfqTe+iETw0MtGdjlqckYhrcZGQmJQ2r7lAhTHi0LV513qGYUvcds7NUuNY 1GMz0jvC6hcBk6JlaWAN/cqaIonYJhpBn4mIVF7h71WAKsg35Hcm5UiiTeCaTQMK3VMRKt eCTFZcMnj8HsMeeOREjuVTHlb+uEdXk= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 87FC943584; Tue, 22 Sep 2026 23:00:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2DD81F000FF; Tue, 22 Sep 2026 23:00:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790118024; bh=67Wnb1WqUtfvvqvCH5gthEhN54uXfj3OJmtQ8451vqc=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=f4enYMEQW7QizF7EO1g1cQ4u8gA82wou/SQ/2W3Thvjli+h6aobD5ZlJDs/jfh1FV zSB+Kfk4FuUqyw9bmcvk46t07MCBzK0NBIy1fjrGw3Rhfy7nWNjaUOxIcpoiKWtmMx CWvPp7SZoe+aH84d+5DNVA8gveOr1sRQo2MPtAwc= Date: Tue, 22 Sep 2026 16:00:21 -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 , 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 , Yoshinori Sato , Shakeel Butt , Jonathan Corbet , Randy Dunlap , 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 , linux-doc@vger.kernel.org Subject: Re: [PATCH v4 00/12] mm: make userland page table freeing RCU-safe Message-Id: <20260922160021.a2fc65d05d9b867a141e5457@linux-foundation.org> In-Reply-To: <20260922-rcu-pagetable-freeing-v4-0-fe1ad1f1e303@kernel.org> References: <20260922-rcu-pagetable-freeing-v4-0-fe1ad1f1e303@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 3scejeoryejwrpzcgstarfrxzmru79pe X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5D186160005 X-HE-Tag: 1790118026-824905 X-HE-Meta: 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 mLl+pMs8 mYL3KuWj3VhiI7qLjlvbqY2QlhyimdNviam17nA/PKphH/a9sYVxpiVqWgmCWp1fmrTnBaorwbku+QWEtcJj3lc7tgRZdUc6lQ+AsiHl8C2AAicAMrF+Wo39RvHUaqzEzhXzJf5WEaCQARUvjEbxbJb5KpnYx14fSEEeI78TgM3CiXUhNmldklh5Kaw5xshW+E7fqaM3FrHfc0jvQfhX/lbBMUBL1iOot1CeKpFH0pNQCbMBa4IR++nmJZgRMwmuhVU177gbQ3R3U+G44hVmYHl/Oo7It9GZTHtUb5VRz3Qlc/uOWtkMxOo+5PDwKei9xiOJ4KIIvkzM7Wm6g3iwpcaB59m2e7/brObGW Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 22 Sep 2026 16:35:31 +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. Do we have reason to believe that anyone is seeing any effects from their arch's failure to rcu-free the page tables? This sounds like a rather long-standing wart, yes? The patchset is thinly reviewed and mm.git is bursting at the seams again. I'll play wait-and-see on this series. Feel free to cluebat me if that's a bad call.