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 X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 349B7C04A6B for ; Wed, 8 May 2019 16:43:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0AEF421726 for ; Wed, 8 May 2019 16:43:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728612AbfEHQn5 (ORCPT ); Wed, 8 May 2019 12:43:57 -0400 Received: from foss.arm.com ([217.140.101.70]:40270 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727786AbfEHQn4 (ORCPT ); Wed, 8 May 2019 12:43:56 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EF3F1374; Wed, 8 May 2019 09:43:55 -0700 (PDT) Received: from [10.1.196.93] (en101.cambridge.arm.com [10.1.196.93]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 31F693F238; Wed, 8 May 2019 09:43:55 -0700 (PDT) Subject: Re: [PATCH 1/2] coresight: Do not call smp_processor_id() from preemptible To: mathieu.poirier@linaro.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org References: <1556899459-27785-1-git-send-email-suzuki.poulose@arm.com> From: Suzuki K Poulose Message-ID: Date: Wed, 8 May 2019 17:43:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/05/2019 17:39, Mathieu Poirier wrote: > Hi Suzuki, > > On Fri, 3 May 2019 at 10:04, Suzuki K Poulose wrote: >> >> Instead of using smp_processor_id() to figure out the node, >> use the numa_node_id() for the current CPU node to avoid >> splats like : >> >> BUG: using smp_processor_id() in preemptible [00000000] code: perf/1743 >> caller is alloc_etr_buf.isra.6+0x80/0xa0 >> CPU: 1 PID: 1743 Comm: perf Not tainted 5.1.0-rc6-147786-g116841e #344 >> Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb 1 2019 >> Call trace: >> dump_backtrace+0x0/0x150 >> show_stack+0x14/0x20 >> dump_stack+0x9c/0xc4 >> debug_smp_processor_id+0x10c/0x110 >> alloc_etr_buf.isra.6+0x80/0xa0 >> tmc_alloc_etr_buffer+0x12c/0x1f0 >> etm_setup_aux+0x1c4/0x230 >> rb_alloc_aux+0x1b8/0x2b8 >> perf_mmap+0x35c/0x478 >> mmap_region+0x34c/0x4f0 >> do_mmap+0x2d8/0x418 >> vm_mmap_pgoff+0xd0/0xf8 >> ksys_mmap_pgoff+0x88/0xf8 >> __arm64_sys_mmap+0x28/0x38 >> el0_svc_handler+0xd8/0x138 >> el0_svc+0x8/0xc >> > > That is very interesting... > >> Fixes: 855ab61c16bf70b646 ("coresight: tmc-etr: Refactor function tmc_etr_setup_perf_buf()") >> Cc: Mathieu Poirier >> Signed-off-by: Suzuki K Poulose >> --- >> drivers/hwtracing/coresight/coresight-tmc-etr.c | 6 ++---- >> 1 file changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> index 793639f..74578bd 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c >> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> @@ -1323,13 +1323,11 @@ static struct etr_perf_buffer * >> tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, struct perf_event *event, >> int nr_pages, void **pages, bool snapshot) >> { >> - int node, cpu = event->cpu; >> + int node; >> struct etr_buf *etr_buf; >> struct etr_perf_buffer *etr_perf; >> >> - if (cpu == -1) >> - cpu = smp_processor_id(); >> - node = cpu_to_node(cpu); >> + node = (event->cpu == -1)? numa_node_id() : cpu_to_node(event->cpu); > > Seems to me using numa_node_id() simply circumvent function > debug_smp_processor_id() and using get_cpu() and put_cpu() would be > more appropriate. But I'll trust the NUMA people have thought about > this long before me. Would you mind sending another revision that fix > the same code for ETB and ETF? Sure, will send it soon. Suzuki