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 D40ACC7618A for ; Mon, 20 Mar 2023 11:48:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229493AbjCTLsp (ORCPT ); Mon, 20 Mar 2023 07:48:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230251AbjCTLso (ORCPT ); Mon, 20 Mar 2023 07:48:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC6C91588F for ; Mon, 20 Mar 2023 04:48:43 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 580C86148A for ; Mon, 20 Mar 2023 11:48:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62CDBC433EF; Mon, 20 Mar 2023 11:48:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1679312922; bh=wYeP0xRZaYl0VrjJghbv7YIjc//kQmN/mc5R4CD+8To=; h=Subject:To:Cc:From:Date:From; b=N1i26ci5zZkVr+RHJAizEjxGtwcny7J+K1RN5bHKbAgDulSfvOQt2HbB9jbqP15Is 7YAEfTwIwim1t/m/f/Tyf0zKKCU8u51uC52edhxd/qZ9ulibD6OkFZ3l51Buko1WQ4 MVT/ssBmTbDg19MisTIJRA4y7zSAYDz1zXmNjMsU= Subject: FAILED: patch "[PATCH] trace/hwlat: Do not start per-cpu thread if it is already" failed to apply to 5.15-stable tree To: tero.kristo@linux.intel.com, bristot@kernel.org, rostedt@goodmis.org Cc: From: Date: Mon, 20 Mar 2023 12:48:39 +0100 Message-ID: <167931291995243@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 08697bca9bbba15f2058fdbd9f970bd5f6a8a2e8 # git commit -s git send-email --to '' --in-reply-to '167931291995243@kroah.com' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 08697bca9bbb ("trace/hwlat: Do not start per-cpu thread if it is already running") ff78f6679d2e ("trace/hwlat: make use of the helper function kthread_run_on_cpu()") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 08697bca9bbba15f2058fdbd9f970bd5f6a8a2e8 Mon Sep 17 00:00:00 2001 From: Tero Kristo Date: Fri, 10 Mar 2023 12:04:51 +0200 Subject: [PATCH] trace/hwlat: Do not start per-cpu thread if it is already running The hwlatd tracer will end up starting multiple per-cpu threads with the following script: #!/bin/sh cd /sys/kernel/debug/tracing echo 0 > tracing_on echo hwlat > current_tracer echo per-cpu > hwlat_detector/mode echo 100000 > hwlat_detector/width echo 200000 > hwlat_detector/window echo 1 > tracing_on To fix the issue, check if the hwlatd thread for the cpu is already running, before starting a new one. Along with the previous patch, this avoids running multiple instances of the same CPU thread on the system. Link: https://lore.kernel.org/all/20230302113654.2984709-1-tero.kristo@linux.intel.com/ Link: https://lkml.kernel.org/r/20230310100451.3948583-3-tero.kristo@linux.intel.com Cc: stable@vger.kernel.org Fixes: f46b16520a087 ("trace/hwlat: Implement the per-cpu mode") Signed-off-by: Tero Kristo Acked-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google) diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index edc26dc22c3f..c4945f8adc11 100644 --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -492,6 +492,10 @@ static int start_cpu_kthread(unsigned int cpu) { struct task_struct *kthread; + /* Do not start a new hwlatd thread if it is already running */ + if (per_cpu(hwlat_per_cpu_data, cpu).kthread) + return 0; + kthread = kthread_run_on_cpu(kthread_fn, NULL, cpu, "hwlatd/%u"); if (IS_ERR(kthread)) { pr_err(BANNER "could not start sampling thread\n");