From nobody Sun Feb 8 05:53:53 2026 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 429E4C7EE23 for ; Tue, 23 May 2023 14:12:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237234AbjEWOMt (ORCPT ); Tue, 23 May 2023 10:12:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51140 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236937AbjEWOMY (ORCPT ); Tue, 23 May 2023 10:12:24 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80E351AE for ; Tue, 23 May 2023 07:12:04 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-1ae4c5e1388so70758635ad.1 for ; Tue, 23 May 2023 07:12:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1684851124; x=1687443124; h=message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JOv8NfcQjNQA77R6r5WpnsvLvT0EoI9tnHd1ASgA//M=; b=NvdjK01a3xo4nQVj/srjU9AzEk3tK1ASeQXNfLF+9Bq4q0PsxrsG1cb1xFA97XaFJT K0EKk5nOHdfpF4Ne913j63t+l/wIHqxA5jRiaikboXplBRa7ndTXRKOLQzvIo0OTjokB JnkvdB/P9w/aQI5eOL/q8OlnlO81iZs9k7MYdEF3ErBa/TtoGAR/F+7Z9mMij0vlUW5A lWLik/xV6XaHdbyVwicUSr8k5vTXQFJydaAkdd7JxkGEIDorVFLtcEDd895qnsy8/yL6 j2+NQfLdZv+fC/5JI5mYI1kT5yeyCTY1hLOZbvCSidUr+tMmF/kdWv4NDWOaqNnrjGoI GPag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684851124; x=1687443124; h=message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=JOv8NfcQjNQA77R6r5WpnsvLvT0EoI9tnHd1ASgA//M=; b=ZLUHZjIQhZEMMiNIcHOQkmqA8t0LERnvOGtTiGAEht5DiP+JahAboYGQAVPBnMTc++ a8RgobxnwNZGRYKTAzMspXApXPa5cdENKXLetKiF/EzOpSkXj+BW9FyiBwDudlcb9BjW mVh9mn/DzDgqPmElImk9AIWoGbluWe8nJnci0Wh1RbQ+CQg/RcMauiYt5Yx1d1oaOD7h gsSapOXHeb1Utu6+tu/yaG+k5NeTB2ESscO4qYWQDORhNbTGqcRqFrSWsEXOTI0QaNMr MvGVn8L64R+viqfkbbaIdG9pI1yDFUazNukzgvTh/Qh64sP5XcA/q781Eyewj+FfXadH QHDw== X-Gm-Message-State: AC+VfDxZ78o6ij8T7YQL1uK9kb+4tjQeCGHFdwLNP9UM+DNKfTHaaP55 HYYy0eb0xJjv9qEZ6v19pN8= X-Google-Smtp-Source: ACHHUZ6HrjWU1CF0VhgPjXJNlZHb6MbE97XjzyUOPvxDc0pZMB6O1X3FG652/Ma4XaVVxayKZ6O6Eg== X-Received: by 2002:a17:903:1251:b0:1ac:451d:34a with SMTP id u17-20020a170903125100b001ac451d034amr16957690plh.33.1684851123743; Tue, 23 May 2023 07:12:03 -0700 (PDT) Received: from localhost.localdomain ([124.126.151.211]) by smtp.gmail.com with ESMTPSA id jl1-20020a170903134100b00194caf3e975sm6789013plb.208.2023.05.23.07.12.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 May 2023 07:12:03 -0700 (PDT) From: Zqiang To: tj@kernel.org, jiangshanlai@gmail.com, naresh.kamboju@linaro.org, qiang.zhang1211@gmail.com Cc: linux-kernel@vger.kernel.org Subject: [PATCH v2] workqueue: Fix warning triggered when nr_running is checked in worker_enter_idle() Date: Tue, 23 May 2023 22:09:41 +0800 Message-Id: <20230523140942.18679-1-qiang.zhang1211@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Currently, the nr_running can be modified from timer tick, that means the timer tick can run in not-irq-protected critical section to modify nr_runnig, consider the following scenario: CPU0 kworker/0:2 (events) worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); ->pool->nr_running++; (1) process_one_work() ->worker->current_func(work); ->schedule() ->wq_worker_sleeping() ->worker->sleeping =3D 1; ->pool->nr_running--; (0) .... ->wq_worker_running() .... CPU0 by interrupt: wq_worker_tick() ->worker_set_flags(worker, WORKER_CPU_INTENSIVE); ->pool->nr_running--; (-1) ->worker->flags |=3D WORKER_CPU_INTENSIVE; .... ->if (!(worker->flags & WORKER_NOT_RUNNING)) ->pool->nr_running++; (will not execute) ->worker->sleeping =3D 0; .... ->worker_clr_flags(worker, WORKER_CPU_INTENSIVE); ->pool->nr_running++; (0) .... worker_set_flags(worker, WORKER_PREP); ->pool->nr_running--; (-1) .... worker_enter_idle() ->WARN_ON_ONCE(pool->nr_workers =3D=3D pool->nr_idle && pool->nr_runnin= g); if the nr_workers is equal to nr_idle, due to the nr_running is not zero, will trigger WARN_ON_ONCE(). [ 2.460602] WARNING: CPU: 0 PID: 63 at kernel/workqueue.c:1999 worker_en= ter_idle+0xb2/0xc0 [ 2.462163] Modules linked in: [ 2.463401] CPU: 0 PID: 63 Comm: kworker/0:2 Not tainted 6.4.0-rc2-next-= 20230519 #1 [ 2.463771] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.1= 4.0-2 04/01/2014 [ 2.465127] Workqueue: 0x0 (events) [ 2.465678] RIP: 0010:worker_enter_idle+0xb2/0xc0 ... [ 2.472614] Call Trace: [ 2.473152] [ 2.474182] worker_thread+0x71/0x430 [ 2.474992] ? _raw_spin_unlock_irqrestore+0x28/0x50 [ 2.475263] kthread+0x103/0x120 [ 2.475493] ? __pfx_worker_thread+0x10/0x10 [ 2.476355] ? __pfx_kthread+0x10/0x10 [ 2.476635] ret_from_fork+0x2c/0x50 [ 2.477051] This commit therefore add the check of worker->sleeping in wq_worker_tick(), if the worker->sleeping is not zero, directly return. Reported-by: Naresh Kamboju Closes: https://qa-reports.linaro.org/lkft/linux-next-master/build/next-202= 30519/testrun/17078554/suite/boot/test/clang-nightly-lkftconfig/log Signed-off-by: Zqiang --- kernel/workqueue.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 9c5c1cfa478f..329b84c42062 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1144,13 +1144,12 @@ void wq_worker_tick(struct task_struct *task) * longer than wq_cpu_intensive_thresh_us, it's automatically marked * CPU_INTENSIVE to avoid stalling other concurrency-managed work items. */ - if ((worker->flags & WORKER_NOT_RUNNING) || + if ((worker->flags & WORKER_NOT_RUNNING) || worker->sleeping || worker->task->se.sum_exec_runtime - worker->current_at < wq_cpu_intensive_thresh_us * NSEC_PER_USEC) return; =20 raw_spin_lock(&pool->lock); - worker_set_flags(worker, WORKER_CPU_INTENSIVE); wq_cpu_intensive_report(worker->current_func); pwq->stats[PWQ_STAT_CPU_INTENSIVE]++; --=20 2.17.1