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 09593C7EE25 for ; Thu, 8 Jun 2023 12:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236193AbjFHMkv (ORCPT ); Thu, 8 Jun 2023 08:40:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231626AbjFHMkt (ORCPT ); Thu, 8 Jun 2023 08:40:49 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B61A726B3; Thu, 8 Jun 2023 05:40:46 -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 AF8F31042; Thu, 8 Jun 2023 05:41:31 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.24.103]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 895CD3F663; Thu, 8 Jun 2023 05:40:44 -0700 (PDT) Date: Thu, 8 Jun 2023 13:40:39 +0100 From: Mark Rutland To: Junhao He , will@kernel.org Cc: jonathan.cameron@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linuxarm@huawei.com, yangyicong@huawei.com, shenyang39@huawei.com, prime.zeng@hisilicon.com Subject: Re: [PATCH] drivers/perf: hisi: Don't migrate perf to the CPU going to teardown Message-ID: References: <20230608114326.27649-1-hejunhao3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230608114326.27649-1-hejunhao3@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 08, 2023 at 07:43:26PM +0800, Junhao He wrote: > The driver needs to migrate the perf context if the current using CPU going > to teardown. By the time calling the cpuhp::teardown() callback the > cpu_online_mask() hasn't updated yet and still includes the CPU going to > teardown. In current driver's implementation we may migrate the context > to the teardown CPU and leads to the below calltrace: > > ... > [ 368.104662][ T932] task:cpuhp/0 state:D stack: 0 pid: 15 ppid: 2 flags:0x00000008 > [ 368.113699][ T932] Call trace: > [ 368.116834][ T932] __switch_to+0x7c/0xbc > [ 368.120924][ T932] __schedule+0x338/0x6f0 > [ 368.125098][ T932] schedule+0x50/0xe0 > [ 368.128926][ T932] schedule_preempt_disabled+0x18/0x24 > [ 368.134229][ T932] __mutex_lock.constprop.0+0x1d4/0x5dc > [ 368.139617][ T932] __mutex_lock_slowpath+0x1c/0x30 > [ 368.144573][ T932] mutex_lock+0x50/0x60 > [ 368.148579][ T932] perf_pmu_migrate_context+0x84/0x2b0 > [ 368.153884][ T932] hisi_pcie_pmu_offline_cpu+0x90/0xe0 [hisi_pcie_pmu] > [ 368.160579][ T932] cpuhp_invoke_callback+0x2a0/0x650 > [ 368.165707][ T932] cpuhp_thread_fun+0xe4/0x190 > [ 368.170316][ T932] smpboot_thread_fn+0x15c/0x1a0 > [ 368.175099][ T932] kthread+0x108/0x13c > [ 368.179012][ T932] ret_from_fork+0x10/0x18 > ... > > Use function cpumask_any_but() to find one correct active cpu to fixes > this issue. > > Fixes: 8404b0fbc7fb ("drivers/perf: hisi: Add driver for HiSilicon PCIe PMU") > Signed-off-by: Junhao He Acked-by: Mark Rutland I assume that Will can pick this up. I did a quick check, and all other perf drivers seem to do the right thing here, either using cpumask_any_but(), or generating a temporary mask with the cpu being offlined removed. Mark. > --- > drivers/perf/hisilicon/hisi_pcie_pmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/perf/hisilicon/hisi_pcie_pmu.c b/drivers/perf/hisilicon/hisi_pcie_pmu.c > index 0bc8dc36aff5..14f8b4b03337 100644 > --- a/drivers/perf/hisilicon/hisi_pcie_pmu.c > +++ b/drivers/perf/hisilicon/hisi_pcie_pmu.c > @@ -683,7 +683,7 @@ static int hisi_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) > > pcie_pmu->on_cpu = -1; > /* Choose a new CPU from all online cpus. */ > - target = cpumask_first(cpu_online_mask); > + target = cpumask_any_but(cpu_online_mask, cpu); > if (target >= nr_cpu_ids) { > pci_err(pcie_pmu->pdev, "There is no CPU to set\n"); > return 0; > -- > 2.30.0 >