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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C37ECC433DB for ; Mon, 22 Feb 2021 13:44:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C10364E74 for ; Mon, 22 Feb 2021 13:44:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231347AbhBVNoV (ORCPT ); Mon, 22 Feb 2021 08:44:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230425AbhBVNlF (ORCPT ); Mon, 22 Feb 2021 08:41:05 -0500 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2F73C061574 for ; Mon, 22 Feb 2021 05:40:22 -0800 (PST) Received: by mail-pg1-x52e.google.com with SMTP id l2so170652pgb.1 for ; Mon, 22 Feb 2021 05:40:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=DrA5z8COmcoHf40X8aYrpFjyoaTw3sNPCWnlWiiL4ik=; b=M9k9Ij/9tj9iE05599VLlIAIjxdMxledHwbsdpFbVwQtNgLdA/1cvWFAcWHAC9s77Y YOLP6U8ht3nMDXTvjal2nEmXGJniZRah4YYvgPiUwFUQbFmrHWDSpQNRj92uSfwu7UZB bFvbjJ0Up4c6vnTDvgPFHzj9qn8GXSDlRsy8BhkWNPqmyTNDD0hM3h5dqv6LByaMSPY2 LhTU3VXWkgt//9lR/rPC7mH4h5qYLZ9jwczwS0irSv4n+RHgMCrGwy95YxL0qr3DzRdU M/ZLENgSv5xfjuxUgoq+hzlKGdterw63kpTNFlJMNbquTN36wcCV2NX586vhP1UT71Wf phDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=DrA5z8COmcoHf40X8aYrpFjyoaTw3sNPCWnlWiiL4ik=; b=WvnIjLGw1piOzAyol0OS7WC23FaoulE94n9nTbtCbDwNytjMGieF9cXLtgq43/6K0Y lwOOfWgq05tVFdSLfw+5p385FKOxh17FgHg/4DD7IiGPK1X+5R/4B7PDgK7P7UdcMjqg ru1bK5NnQBqfUbdvBbxY1zWD44cOVJxvw+IHhm0d8v/mSQY0igoqLAkrb+xT5rzBVKcX qequdqq03IXqvYLIhORRCgHNnoHu+jk3fJjyluwByHoZP+iRgtodGZ3LwXkTYlUdm1Tm nh3zhSfjhx5C8dpHc49NRqIdguQqld54/SgBwEdj/X2E6lpRKyVNswtbIaVOmrHiQrvR um6A== X-Gm-Message-State: AOAM531lVpEV/IXIgUW8oGhVHFJ5SrODu2JLTorEIpmCOXcvNLvk9FqS 11WP7G1acUgmvFHe4fpDr4HokA== X-Google-Smtp-Source: ABdhPJylBpFvlZLsCQ5qUkFRkLmxKfyy1QlVatJDMeH4jCua6UnI5i4ip27RIQsUYmZeMY008hKovg== X-Received: by 2002:a63:397:: with SMTP id 145mr19745749pgd.171.1614001222199; Mon, 22 Feb 2021 05:40:22 -0800 (PST) Received: from [192.168.1.134] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id s16sm8552732pfs.39.2021.02.22.05.40.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Feb 2021 05:40:21 -0800 (PST) Subject: Re: [PATCH] block: fix potential IO hang when turning off io_poll To: Jeffle Xu Cc: linux-block@vger.kernel.org, io-uring@vger.kernel.org, joseph.qi@linux.alibaba.com References: <20210222065452.21897-1-jefflexu@linux.alibaba.com> From: Jens Axboe Message-ID: <9b4dfa03-060b-dcd7-f897-106dc395fd3c@kernel.dk> Date: Mon, 22 Feb 2021 06:40:22 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210222065452.21897-1-jefflexu@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2/21/21 11:54 PM, Jeffle Xu wrote: > QUEUE_FLAG_POLL flag will be cleared when turning off 'io_poll', while > at that moment there may be IOs stuck in hw queue uncompleted. The > following polling routine won't help reap these IOs, since blk_poll() > will return immediately because of cleared QUEUE_FLAG_POLL flag. Thus > these IOs will hang until they finnaly time out. The hang out can be > observed by 'fio --engine=io_uring iodepth=1', while turning off > 'io_poll' at the same time. > > To fix this, freeze and flush the request queue first when turning off > 'io_poll'. Applied, thanks. Fixed up the braces. -- Jens Axboe