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 1A895C33C9E for ; Wed, 8 Jan 2020 11:00:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E532020692 for ; Wed, 8 Jan 2020 11:00:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728014AbgAHLAk (ORCPT ); Wed, 8 Jan 2020 06:00:40 -0500 Received: from foss.arm.com ([217.140.110.172]:42304 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726290AbgAHLAj (ORCPT ); Wed, 8 Jan 2020 06:00:39 -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 2868030E; Wed, 8 Jan 2020 03:00:39 -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 76E0C3F703; Wed, 8 Jan 2020 03:00:38 -0800 (PST) Subject: Re: [PATCH 4.19 102/115] coresight: tmc-etf: 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> <20200107205308.269793829@linuxfoundation.org> From: Suzuki Kuruppassery Poulose Message-ID: Date: Wed, 8 Jan 2020 11:00:37 +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: <20200107205308.269793829@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 Hi Greg, On 07/01/2020 20:55, Greg Kroah-Hartman wrote: > From: Suzuki K Poulose > > [ Upstream commit 024c1fd9dbcc1d8a847f1311f999d35783921b7f ] > > 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 > caller is tmc_alloc_etf_buffer+0x5c/0x60 > Fixes: 2e499bbc1a929ac ("coresight: tmc: implementing TMC-ETF AUX space API") > Cc: Mathieu Poirier > Signed-off-by: Suzuki K Poulose > Cc: stable # 4.7+ > Signed-off-by: Mathieu Poirier > Link: https://lore.kernel.org/r/20190620221237.3536-4-mathieu.poirier@linaro.org > Signed-off-by: Greg Kroah-Hartman > Signed-off-by: Sasha Levin > --- > drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c > index e31061308e19..4644ac5582cf 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c > @@ -304,9 +304,7 @@ static void *tmc_alloc_etf_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); This will break the build on v4.19 to v4.9 as event was not available to the routine. So please drop this one for now. I will post a backport separately. Suzuki