From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F187C60A6F69 for ; Wed, 28 Oct 2026 15:44:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=lThYSxZo; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=DvmFqyUy DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=CAt0d5ylylt8eW+LlxYd6ss54lXkb9DQcvfjrPX+Thw=; b=lThYSxZogyeiRrgpcQyjdGs976 wcaD5JbyKhA0wdm3P4dz7gMRPximgij2r9FQO3MGshDNlwTdJ9Zsa4vgC9EpEfXz8aQH5h9ElEr7k KP9oaPHVrqwGnlz4waqikgJwD4hPIWe85lWtVMrA6DF0uLAktfIubKPz/ZrXOPBqehh1uZO111uAm TMVCwCbl1nN/3svKsAacqlJwvKvhrHAZHClkqVkZRO4JS5goNCVQkAOUF7AuoKSpLAbeBWm7PLHAk YBySwFB2JlIKJ9EODmZgPJh33iqcABJr2X/GtBw6JcZFTKhWLjyEcyiIO4Vl4GB+kxrjlMC4imN7l QokzsqfA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM5Xd-00000007MyV-3DTo; Wed, 28 Oct 2026 15:26:17 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM5Xd-00000007My9-05Ep for linux-arm-kernel@lists.infradead.org; Wed, 28 Oct 2026 15:26:17 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1E929445E8; Wed, 28 Oct 2026 15:26:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 678FE1F031E1; Wed, 28 Oct 2026 15:26:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793201176; bh=CAt0d5ylylt8eW+LlxYd6ss54lXkb9DQcvfjrPX+Thw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=DvmFqyUySHpUvxKNU6qRygBZIY+lpdJ+uHpVbKHq9HS5UeSmcmMC9dUBwX8iplhrZ wCHmTngQ6m83iipwvMqWvn3IUGbaNt9zogpn9Tp+Ob/VgyZ4II59nTZtZQLAfuvfwE 0hpm1yZ9gjXNlmyOeHYzLeThFwP82DNITlZLKDF/L6Zk9rec/VtkPyvQvinfK5KzRv ONFcMyomZVlIuh4f8id5FMbupEKeJ+ijJdHaY6AQGVVCnnkhXNe3dL4ggz9L4g2fyw VEeC6jaaAeDUVADLBMab9KSR8q0m7UId7hfUpA/1rIw7Ltv+XiGqYhBScioArXDrCo vZlyQ1qegZTpg== Date: Wed, 28 Oct 2026 16:26:13 +0100 From: Frederic Weisbecker To: Florian Fainelli Cc: LKML , Broadcom internal kernel review list , Marco Crivellari , Peter Zijlstra , Phil Auld , Russell King , Thomas Gleixner , Waiman Long , linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH 49/49] ARM: mm: Move CPUHP_AP_ARM_CACHE_B15_RAC_DYING post stop_machine() Message-ID: References: <20261019130856.49711-1-frederic@kernel.org> <20261019130856.49711-50-frederic@kernel.org> <1f1260db-09df-4d42-bfc7-34f9a787176a@broadcom.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1f1260db-09df-4d42-bfc7-34f9a787176a@broadcom.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Le Fri, Oct 23, 2026 at 10:05:30AM -0700, Florian Fainelli a écrit : > On 10/19/26 06:08, Frederic Weisbecker wrote: > > Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes > > all the teardown callbacks while stopping all CPUs in the system. This > > doesn't mix-up well with running RT or isolated tasks. > > > > In order to transition smoothly from global stop_machine to finer > > grained synchronization between teardown callbacks and the other CPUs, > > a new stop machine post function has been introduced to be executed > > after the main one with IRQs still disabled while other CPUs can exit > > stop_machine(). > > > > It *looks ok* to disable the cache readahead globally while the other > > CPUs are running. > > Yes I think it is safe given that b15_rac_dying_cpu() will run on the dying > CPU and any CPU that is left will basically re-enable the RAC afterwards if > necessary in b15_rac_dead_cpu(). Good. > > The hardware to test this is quite ancient, but if you give me a test case > to exercise, I can give it a spin. I don't have the hardware either. Otherwise the only test I can think of is to simply shutdown a CPU and see if that explodes. Thanks! > > Thank you Frederic! > -- > Florian -- Frederic Weisbecker SUSE Labs