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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B90AEC43334 for ; Thu, 14 Jul 2022 17:52:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240458AbiGNRwy (ORCPT ); Thu, 14 Jul 2022 13:52:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231500AbiGNRww (ORCPT ); Thu, 14 Jul 2022 13:52:52 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 13669491D1 for ; Thu, 14 Jul 2022 10:52:52 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4062C1D13; Thu, 14 Jul 2022 10:52:52 -0700 (PDT) Received: from localhost (ionvoi01-desktop.cambridge.arm.com [10.1.196.65]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6883F3F70D; Thu, 14 Jul 2022 10:52:51 -0700 (PDT) Date: Thu, 14 Jul 2022 18:52:49 +0100 From: Ionela Voinescu To: Sudeep Holla Cc: linux-kernel@vger.kernel.org, conor.dooley@microchip.com, Greg Kroah-Hartman , Vincent Guittot , Dietmar Eggemann , Pierre Gondois , linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH -next] arch_topology: Fix cache attributes detection in the CPU hotplug path Message-ID: References: <20220713133344.1201247-1-sudeep.holla@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220713133344.1201247-1-sudeep.holla@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sudeep, Thank you for the fix! On Wednesday 13 Jul 2022 at 14:33:44 (+0100), Sudeep Holla wrote: > init_cpu_topology() is called only once at the boot and all the cache > attributes are detected early for all the possible CPUs. However when > the CPUs are hotplugged out, the cacheinfo gets removed. While the > attributes are added back when the CPUs are hotplugged back in as part > of CPU hotplug state machine, it ends up called quite late after the > update_siblings_masks() are called in the secondary_start_kernel() > resulting in wrong llc_sibling_masks. > > Move the call to detect_cache_attributes() inside update_siblings_masks() > to ensure the cacheinfo is updated before the LLC sibling masks are > updated. This will fix the incorrect LLC sibling masks generated when > the CPUs are hotplugged out and hotplugged back in again. > > Reported-by: Ionela Voinescu > Signed-off-by: Sudeep Holla > --- > drivers/base/arch_topology.c | 16 ++++++---------- > 1 file changed, 6 insertions(+), 10 deletions(-) > > Hi Conor, > > Ionela reported an issue with the CPU hotplug and as a fix I need to > move the call to detect_cache_attributes() which I had thought to keep > it there from first but for no reason had moved it to init_cpu_topology(). > > Wonder if this fixes the -ENOMEM on RISC-V as this one is called on the > cpu in the secondary CPUs init path while init_cpu_topology executed > detect_cache_attributes() for all possible CPUs much earlier. I think > this might help as the percpu memory might be initialised in this case. > > Anyways give this a try, also test the CPU hotplug and check if nothing > is broken on RISC-V. We noticed this bug only on one platform while > > Regards, > Sudeep > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index 441e14ac33a4..0424b59b695e 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -732,7 +732,11 @@ const struct cpumask *cpu_clustergroup_mask(int cpu) > void update_siblings_masks(unsigned int cpuid) > { > struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid]; > - int cpu; > + int cpu, ret; > + > + ret = detect_cache_attributes(cpuid); > + if (ret) > + pr_info("Early cacheinfo failed, ret = %d\n", ret); > /* update core and thread sibling masks */ > for_each_online_cpu(cpu) { > @@ -821,7 +825,7 @@ __weak int __init parse_acpi_topology(void) > #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) > void __init init_cpu_topology(void) > { > - int ret, cpu; > + int ret; > reset_cpu_topology(); > ret = parse_acpi_topology(); > @@ -836,13 +840,5 @@ void __init init_cpu_topology(void) > reset_cpu_topology(); > return; > } > - > - for_each_possible_cpu(cpu) { > - ret = detect_cache_attributes(cpu); > - if (ret) { > - pr_info("Early cacheinfo failed, ret = %d\n", ret); > - break; > - } > - } > } > #endif > --2.37.1 > Reviewed-by: Ionela Voinescu Tested-by: Ionela Voinescu Kind regards, Ionela.