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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 245B3C43331 for ; Fri, 3 Apr 2020 14:53:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E799A206F5 for ; Fri, 3 Apr 2020 14:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585925611; bh=mZm2UukruDWuzMgf1nzUV9ZDd1DY335QNWej4RBvLBY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Fn7goXmfGYz/Zs77bduUwqk54fe+yJoTg5hO+Q82XfsABt+bCCiIEwuOobj1q4A5a BlMiwTpHV4PUkeQXlxrOvUtaGE12rjqmZTDBnn9fpq7oD+PyF/Sw0WbiF6fWp0EhB2 zp/9NjnTRO8ILVOpE0LtxhA6/4/jIyGoG6F6EbH8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391089AbgDCOx3 (ORCPT ); Fri, 3 Apr 2020 10:53:29 -0400 Received: from mail-qv1-f67.google.com ([209.85.219.67]:38027 "EHLO mail-qv1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390784AbgDCOx3 (ORCPT ); Fri, 3 Apr 2020 10:53:29 -0400 Received: by mail-qv1-f67.google.com with SMTP id p60so3698070qva.5 for ; Fri, 03 Apr 2020 07:53:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=Uc42AQH4tToZy2skrxtoTfXeI+xoeSzapyZv5SU0eo8=; b=qf4g+hbbcI/nBowNBtDb64ExHtqIFgPwdjiy0Nc7tu0Oq3oyONhWJ/Rr1g6UD0QZs0 Bx5WVGtBzAxHTe9WAqe23oKGOR2/ckREp5n1aH/r/ekokqmznvBbvWallZqdM4O4IDeS 87EmF5B8It01mdLwudKlaAiejDjC75Wf/eF8Upl+DHWWqE8XGSDPSZDlMIs2F2KuUd5V 5FxpIA9XCjfgncNwPFgyVYgoU8ylH720rVD97Cpf/kuKwv+hSs2fDYfKgxn7I26gAX5z xK0U9kFzv5ukf7nKXabOEyF22Ajf9JuEG9sLhPoL/CUiX3QZ/9JsMIqwd57KJmC7Ygvr zLpw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=Uc42AQH4tToZy2skrxtoTfXeI+xoeSzapyZv5SU0eo8=; b=VLnqRjUu2aRj2a6P2ze9KRzHTfNUv3y1ovX2twKkkyPSKmIf58HIseF5iYFPrMEKxg 7fciow0mbCK8/gbCUekAh3ZnRNwuV7088WI5gFT6EX5dYfLISa9e92XPxwUEgmPs+6uR 82JK5jugleku1GQKJAdOCyO0YwI1wWiyF7Lx6ZxSh4mEvzafq8Vbi5RSjvPfQes9QLgc g36XnlPiMEgnBHxIOV9shjz53XCWHnCb0J9u1uiUjDFYFj24zOsbsuTs3jUPQNt9TvkC eXZj40ZsKO3mBsggaxfxt/Aso7SdMEUmtAk0so6b5iHJBARlnhEbsMJoTP3C290OA4Au oOpw== X-Gm-Message-State: AGi0PuYvWGZpErZR+3M19bNbPjZryOWa7tgQmuO1nmp4rh0Z/qcqlS+Z eLPu3yuv3g/Rb16hVqBqyUc= X-Google-Smtp-Source: APiQypKrTR0123hpnS11JtBJkhWIJ/xiXL8/KNpBXkfqK++URN7P9LfsHK2Z8GKTWsO7bJpkwDjOhA== X-Received: by 2002:ad4:498c:: with SMTP id t12mr8849577qvx.27.1585925608121; Fri, 03 Apr 2020 07:53:28 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::842b]) by smtp.gmail.com with ESMTPSA id d2sm6092423qkl.98.2020.04.03.07.53.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2020 07:53:27 -0700 (PDT) Date: Fri, 3 Apr 2020 10:53:26 -0400 From: Tejun Heo To: Sebastian Andrzej Siewior Cc: kernel test robot , Thomas Gleixner , Ingo Molnar , "Peter Zijlstra (Intel)" , linux-kernel@vger.kernel.org, LKP , Lai Jiangshan Subject: Re: [PATCH v2] workqueue: Remove the warning in wq_worker_sleeping() Message-ID: <20200403145326.GA162390@mtj.duckdns.org> References: <20200327074308.GY11705@shao2-debian> <20200327175350.rw5gex6cwum3ohnu@linutronix.de> <20200327232959.rpylymw2edhtxuwr@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200327232959.rpylymw2edhtxuwr@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Sat, Mar 28, 2020 at 12:29:59AM +0100, Sebastian Andrzej Siewior wrote: > The kernel test robot triggered a warning with the following race: > task-ctx A interrupt-ctx B > worker > -> process_one_work() > -> work_item() > -> schedule(); > -> sched_submit_work() > -> wq_worker_sleeping() > -> ->sleeping = 1 > atomic_dec_and_test(nr_running) > __schedule(); *interrupt* > async_page_fault() > -> local_irq_enable(); > -> schedule(); > -> sched_submit_work() > -> wq_worker_sleeping() > -> if (WARN_ON(->sleeping)) return > -> __schedule() > -> sched_update_worker() > -> wq_worker_running() > -> atomic_inc(nr_running); > -> ->sleeping = 0; > > -> sched_update_worker() > -> wq_worker_running() > if (!->sleeping) return > > In this context the warning is pointless everything is fine. This is not a usual control flow, right? Can we annotate this case specifically instead of weakening santiy check for generic cases? Thanks. -- tejun