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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 BDD56C33C9B for ; Wed, 8 Jan 2020 11:01:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95B0E206DA for ; Wed, 8 Jan 2020 11:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727653AbgAHLBn (ORCPT ); Wed, 8 Jan 2020 06:01:43 -0500 Received: from foss.arm.com ([217.140.110.172]:42322 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726276AbgAHLBn (ORCPT ); Wed, 8 Jan 2020 06:01:43 -0500 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 AABF830E; Wed, 8 Jan 2020 03:01:42 -0800 (PST) Received: from [10.1.197.1] (ewhatever.cambridge.arm.com [10.1.197.1]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 073603F703; Wed, 8 Jan 2020 03:01:41 -0800 (PST) Subject: Re: [PATCH 4.19 103/115] coresight: etb10: Do not call smp_processor_id from preemptible To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Mathieu Poirier , Sasha Levin References: <20200107205240.283674026@linuxfoundation.org> <20200107205308.383005810@linuxfoundation.org> From: Suzuki Kuruppassery Poulose Message-ID: Date: Wed, 8 Jan 2020 11:01:41 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200107205308.383005810@linuxfoundation.org> 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 Greg, On 07/01/2020 20:55, Greg Kroah-Hartman wrote: > From: Suzuki K Poulose > > [ Upstream commit 730766bae3280a25d40ea76a53dc6342e84e6513 ] > > During a perf session we try to allocate buffers on the "node" associated > with the CPU the event is bound to. If it is not bound to a CPU, we > use the current CPU node, using smp_processor_id(). However this is unsafe > in a pre-emptible context and could generate the splats as below : > > BUG: using smp_processor_id() in preemptible [00000000] code: perf/2544 > > Use NUMA_NO_NODE hint instead of using the current node for events > not bound to CPUs. > > Fixes: 2997aa4063d97fdb39 ("coresight: etb10: implementing AUX API") > Cc: Mathieu Poirier > Signed-off-by: Suzuki K Poulose > Cc: stable # 4.6+ > Signed-off-by: Mathieu Poirier > Link: https://lore.kernel.org/r/20190620221237.3536-5-mathieu.poirier@linaro.org > Signed-off-by: Greg Kroah-Hartman > Signed-off-by: Sasha Levin > --- > drivers/hwtracing/coresight/coresight-etb10.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c > index 0dad8626bcfb..0a59bf3af40b 100644 > --- a/drivers/hwtracing/coresight/coresight-etb10.c > +++ b/drivers/hwtracing/coresight/coresight-etb10.c > @@ -275,9 +275,7 @@ static void *etb_alloc_buffer(struct coresight_device *csdev, int cpu, > int node; > struct cs_buffers *buf; > > - if (cpu == -1) > - cpu = smp_processor_id(); > - node = cpu_to_node(cpu); > + node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu); Please drop this patch too, from the list as it will break the build with undefined "event" variable. I will post a backport soon. Suzuki