From patchwork Tue Sep 1 11:01:24 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Lorenzo Stoakes (ARM)" X-Patchwork-Id: 2295824 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=xG8XX/3h; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=DiowDP1j; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.infradead.org (client-ip=2607:7c80:54:3::133; helo=bombadil.infradead.org; envelope-from=linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=patchwork.ozlabs.org) Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4hZ32P4wcVz1xy9 for ; Tue, 01 Sep 2026 21:06:21 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References:Message-Id :MIME-Version:Subject:Date:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=NzxDvn/iaIRowR1I7Mfqq8PAfa+NQqZ2EVCvW49O+Ww=; b=xG8XX/3hObIgT3 0F03+f3gOJWjrZW28Jm4a6GElhmi7YUOow7o7rqB2Ccpojedae8VVe55AwYmKhKDTk4jq6TfdwTIR OdE+OtulycFy/pOYQW8gxhbY14kmGhGaZmlc+O257JuMaFZseadhqJA4eyU9j7u5cUzwg0ephNeFj xeed39whuI4BfaRjeljmF81NWYPLm5Rg02mzwmR3MIpcBDDTF7giRtEfZqzw5SeYVYiILPKZGFR4K 94T3+zA9lvF87gjm6rVa3WcgHgJXFjgJmWZrjE2NAC7MkUnud+NdC17o2cykPcSyQ0gcf3AaHD4hn A5D2MUSYYNj8uivkh64w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x1MJn-0000000BdG8-1mSf; Tue, 01 Sep 2026 11:06:19 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x1MJl-0000000BdEj-0PNl; Tue, 01 Sep 2026 11:06:17 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 6DDA642A77; Tue, 1 Sep 2026 11:06:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0F261F01562; Tue, 1 Sep 2026 11:05:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788260773; bh=GKPgtCS/jb8sy+IgthnzqZkszffWbth2i2OdMiXJ3aY=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=DiowDP1j1n5XlCF8U1bsHtuzN012sie75SVdXyIWaQX437ODGamaG8+dyw2U9ubLP ZQuORqY84alF4o7Xnb9l4E4w9MY0R9kv4cXPesYKeaO21X9V5t1J9jM6t8FOU6ikuy rwHNDo3oeWAPjqIeVWVsIP66njOhb+rnrhF3SVDfAj2sWhOXfEfEEsQfd1FnSFpSUT 7uyG08SrjLIgMgvGh2sqL3JbG7jtin7/mj29pE9PwuRoAAnOkJ79fImd5f8RrCs6l7 tyJFWeHJO81hWqDF+lZHR5ixipFciKy/9qPugDinCxm3vBNAzeRoHStXE0TrxYkfq2 AJel7eEB7e32g== From: "Lorenzo Stoakes (ARM)" Date: Tue, 01 Sep 2026 12:01:24 +0100 Subject: [PATCH 04/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for MMU arm MIME-Version: 1.0 Message-Id: <20260901-rcu-pagetable-freeing-v1-4-5456a81c8212@kernel.org> References: <20260901-rcu-pagetable-freeing-v1-0-5456a81c8212@kernel.org> In-Reply-To: <20260901-rcu-pagetable-freeing-v1-0-5456a81c8212@kernel.org> To: Andrew Morton , 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 Cc: 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 , "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1932; i=ljs@kernel.org; h=from:subject:message-id; bh=0gkFDBwGD1EYsdFXWdaAMN6hHbo1XQYIk0QvwnU2gCY=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLKmbXQPjFVa63kgYD1nwDd5n/U/J56e/Sds1bv1xqzfk k9/K/rI01HKwiDGxSArpsjy/Iv4/iCRsHmdF/zdYOawMoEMYeDiFICJyKUzMjyZJ/zbXOdUdfG3 3lVZP8s03GYsefForppMeeA6s8AHPWsYGfYrl/n48ql+/h54kiNrev6UD/E3dxdvOxkQbW9aLfz amBcA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org Commit a0ad5496b2b3 ("arm: mm: enable HAVE_RCU_TABLE_FREE logic") enabled CONFIG_MMU_GATHER_RCU_TABLE_FREE (then named HAVE_RCU_TABLE_FREE) for SMP arm architectures with LPAE enabled. Regardless of whether CONFIG_ARM_LPAE is enabled or not, the same page table freeing functions __pte_free_tlb() and __pmd_free_tlb() are used. Non-LPAE PMD page tables are folded into the PGD and freed by pgd_free() (PGD freeing is not part of mmu_gather page table freeing in any case), so this is a noop in this case. Since commit 358d1c39c82a ("arm: convert various functions to use ptdescs") both LPAE and non-LPAE PTE page table freeing uses tlb_remove_ptdesc(). Thus all page table freeing is performed under RCU with CONFIG_MMU_GATHER_RCU_TABLE_FREE enabled for LPAE and non-LPAE and thus it need not be gated on LPAE. A UP arm system can set CONFIG_PREEMPT_RCU, so a future pure RCU page table walker requires MMU_GATHER_RCU_TABLE_FREE to be enabled on UP as well, even if concurrent GUP fast is not possible there. Therefore, it is both safe and desirable to set CONFIG_MMU_GATHER_RCU_TABLE_FREE for all MMU arm architectures (nommu does not perform mmu_gather operations). This forms part of an overall effort to switch every architecture to this mode. Signed-off-by: Lorenzo Stoakes (ARM) --- arch/arm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 408aa58a2a5b..72b9afc6ae10 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -134,7 +134,7 @@ config ARM select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_POSIX_CPU_TIMERS_TASK_WORK - select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE + select MMU_GATHER_RCU_TABLE_FREE if MMU select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RSEQ select HAVE_RUST if CPU_LITTLE_ENDIAN && CPU_32v7 && !KASAN