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[23.128.96.19]) by mx.google.com with ESMTPS id l3si14861354pls.195.2022.02.15.23.32.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Feb 2022 23:32:08 -0800 (PST) Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 49A61246369; Tue, 15 Feb 2022 22:59:12 -0800 (PST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243756AbiBOWFs (ORCPT + 99 others); Tue, 15 Feb 2022 17:05:48 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:38998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235480AbiBOWFq (ORCPT ); Tue, 15 Feb 2022 17:05:46 -0500 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E34BD1EEE4; Tue, 15 Feb 2022 14:05:35 -0800 (PST) Received: from fsav114.sakura.ne.jp (fsav114.sakura.ne.jp [27.133.134.241]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 21FM58u9053588; Wed, 16 Feb 2022 07:05:08 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav114.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav114.sakura.ne.jp); Wed, 16 Feb 2022 07:05:08 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav114.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 21FM58hL053577 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Wed, 16 Feb 2022 07:05:08 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <06b2f59c-3c96-9443-7a23-f1c957a41d9b@I-love.SAKURA.ne.jp> Date: Wed, 16 Feb 2022 07:05:05 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [syzbot] possible deadlock in worker_thread Content-Language: en-US To: Bart Van Assche , Haakon Bugge Cc: Tejun Heo , syzbot , Jason Gunthorpe , LKML , OFED mailing list , "syzkaller-bugs@googlegroups.com" , Lai Jiangshan References: <0000000000005975a605d7aef05e@google.com> <8ea57ddf-a09c-43f2-4285-4dfb908ad967@acm.org> <71d6f14e-46af-cc5a-bc70-af1cdc6de8d5@acm.org> <309c86b7-2a4c-1332-585f-7bcd59cfd762@I-love.SAKURA.ne.jp> <2959649d-cfbc-bdf2-02ac-053b8e7af030@I-love.SAKURA.ne.jp> <8ebd003c-f748-69b4-3a4f-fb80a3f39d36@I-love.SAKURA.ne.jp> <76616D2F-14F2-4D83-9DB4-576FB2ACB72C@oracle.com> <1b70929f-1f73-c549-64c1-94cea2c1a36c@acm.org> From: Tetsuo Handa In-Reply-To: <1b70929f-1f73-c549-64c1-94cea2c1a36c@acm.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, RCVD_IN_SBL,RDNS_NONE,SPF_HELO_NONE,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/02/16 2:05, Bart Van Assche wrote: > On 2/15/22 04:48, Tetsuo Handa wrote: >> I do not want to do like >> >> -    system_wq = alloc_workqueue("events", 0, 0); >> +    system_wq = alloc_workqueue("events", __WQ_SYSTEM_WIDE, 0); >> >> because the intent of this change is to ask developers to create their own WQs. > > I want more developers to use the system-wide workqueues since that reduces memory usage. That matters for embedded devices running Linux. Reserving a kernel thread for WQ_MEM_RECLAIM WQ might consume some memory, but I don't think that creating a !WQ_MEM_RECLAIM WQ consumes much memory.