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 155A0C433EF for ; Sun, 13 Feb 2022 23:14:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238708AbiBMXGt (ORCPT ); Sun, 13 Feb 2022 18:06:49 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:34322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229453AbiBMXGs (ORCPT ); Sun, 13 Feb 2022 18:06:48 -0500 Received: from mail-pl1-f180.google.com (mail-pl1-f180.google.com [209.85.214.180]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F362254BE0; Sun, 13 Feb 2022 15:06:41 -0800 (PST) Received: by mail-pl1-f180.google.com with SMTP id w20so9160587plq.12; Sun, 13 Feb 2022 15:06:41 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:references:from:in-reply-to :content-transfer-encoding; bh=qhMPRWNoyLemtcbWE/X7+rJB/VYvBTkzYdCumzI+F0g=; b=qlOkEyJnkxRMgJsNIhzSpSkFw2dWDgIiZPhIT0BY1zYY3OPLj7KGI9g5pSKtERrfg+ sVLaAyqyPHMa3wrJ9T7LQXXE3UtnRASNXFj/ZLzBAvvxrSXC8vzyqASu7lX6KLkFKGYe uv3RzKL8lV1+tjPkd2UknEGcyuvlCpp3swfG4WFONwary+PEUIP/zbg8EN9jCIDLiR7+ UzlTsTbblLMqIBIZQbPOnzXTy0CrkNA6vMWoJk+T1buEqelzPPneJVEiBiOvZ5Pxxi/y 2Lyj8rr5JKn45swV4r0Kszi0yuvYPFsBKwayleb/Q9UDYp6jFZnBUy4R+JwtmQKL8KR5 oAkQ== X-Gm-Message-State: AOAM532nG3k1fY2efrr4pj7sDqwHgQMQIiizehQjeoKQEWx+4IxcPnhO ki33zzxrn88TAYGEAysZBko= X-Google-Smtp-Source: ABdhPJynANFxwSs8kCyrzlxuncqnPsAFbwcV+rBe/poFe3AWsvnWVRzINRrykxGM/Y/VwLm6tp648g== X-Received: by 2002:a17:902:d505:: with SMTP id b5mr11660635plg.113.1644793601272; Sun, 13 Feb 2022 15:06:41 -0800 (PST) Received: from ?IPV6:2601:647:4000:d7:feaa:14ff:fe9d:6dbd? ([2601:647:4000:d7:feaa:14ff:fe9d:6dbd]) by smtp.gmail.com with ESMTPSA id 10sm33350391pfm.56.2022.02.13.15.06.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Feb 2022 15:06:40 -0800 (PST) Message-ID: Date: Sun, 13 Feb 2022 15:06:39 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [syzbot] possible deadlock in worker_thread Content-Language: en-US To: Tetsuo Handa , syzbot , jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, syzkaller-bugs@googlegroups.com, Tejun Heo , 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> From: Bart Van Assche In-Reply-To: <309c86b7-2a4c-1332-585f-7bcd59cfd762@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/12/22 09:14, Tetsuo Handa wrote: > How can reviewing all flush_workqueue(system_long_wq) calls help? It is allowed to queue blocking actions on system_long_wq. flush_workqueue(system_long_wq) can make a lower layer (e.g. ib_srp) wait on a blocking action from a higher layer (e.g. the loop driver) and thereby cause a deadlock. Hence my proposal to review all flush_workqueue(system_long_wq) calls. Thanks, Bart.