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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 3C9E9C433DF for ; Tue, 30 Jun 2020 15:02:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 179092073E for ; Tue, 30 Jun 2020 15:02:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QDMn/yh7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728492AbgF3PCW (ORCPT ); Tue, 30 Jun 2020 11:02:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbgF3PCV (ORCPT ); Tue, 30 Jun 2020 11:02:21 -0400 Received: from mail-ej1-x642.google.com (mail-ej1-x642.google.com [IPv6:2a00:1450:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95B1FC061755 for ; Tue, 30 Jun 2020 08:02:21 -0700 (PDT) Received: by mail-ej1-x642.google.com with SMTP id n26so7045097ejx.0 for ; Tue, 30 Jun 2020 08:02:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:references:from:autocrypt:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=snCNHHh5kzI2Jd2z2LXIJGWChkqn97kf+fYxNBn3+Ss=; b=QDMn/yh7hCNCelKpgX7/X+HOVeNIxKzarSCqXRjIpfRW2eqOYA33ZWRhsZxyGv7+wS 23nGJcjiwGmpKgag4H1DCOauPFVDnsU+ktPJf+qvcBibbN084KQNJse/nzxQaYtwT45+ HPbllU9g9tHtZAgGZihp0XzK1oHT0wCToeWYyiyVzMAQfHcpKKCjoB0jlRJk6nLl6o73 QvU6ybfqTNvf4W+W0vcotFqqNxoTI3vMqBuMmMPzGh9AiNTNcdI7/OfzSjrey8S06DyK hC51AJfh6dvbhOaXllkoTXcWAzgKwHfbWo33rtzcXDwqLRc0cHAp0j4o031BIP+KX0LR HEPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:references:from:autocrypt:subject:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=snCNHHh5kzI2Jd2z2LXIJGWChkqn97kf+fYxNBn3+Ss=; b=kI5JV6GM0VLO1Ci4QnsD7WDcmn3+e7GWWxL3By7Kd3Teyx2U+UQ/K8S+pdDuuz6hp2 BbZJhK9JzSJd5m6hZ1h0hOoK9DNnbrZfjcYlYGW+LhQ3sMAwjw/FXqnS8XXylEkElKnV YXO6qbTWAEiCfa+UgFjPemptEmwXcGowI2pembmQCuh9E5yD3fEun86gFfujRK60kvkW nNPwsCbRz7r1j6kzYv2HX3xEvRGP2MTC6Ii1SVn9owRGmeFYanEB749sVuE35ijlfIau bowIdeqIxmloWwC7d2UTFt5JowSad//TDIEQED8dmqb1j4v6oKmfY2OGpM521GTybD49 0/Gg== X-Gm-Message-State: AOAM533vKQfW7OvD7Z5H85nqRcv1/rdBCtWc9PzQc3HuojeT+OUZ1vWl GJy1A9h8RGrnW82qjZ21U3C7QN7u X-Google-Smtp-Source: ABdhPJw9lB8TyzNpdix6AQHvo21AkTH7pHRfukpKYpdFwfYH8XPCx2zeh8Sm9TTuMwxGsNiU+TCiYg== X-Received: by 2002:a17:906:fcb1:: with SMTP id qw17mr17983963ejb.445.1593529340051; Tue, 30 Jun 2020 08:02:20 -0700 (PDT) Received: from [192.168.43.125] ([5.100.193.85]) by smtp.gmail.com with ESMTPSA id k23sm2215994ejo.120.2020.06.30.08.02.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jun 2020 08:02:19 -0700 (PDT) To: Jens Axboe , io-uring@vger.kernel.org References: <75e5bc4f60d751239afa5d7bf2ec9b49308651ac.1593519186.git.asml.silence@gmail.com> <65675178-365d-c859-426b-c0811a2647a3@kernel.dk> <6c499cf3-418d-2edf-d308-2bb5a8d1d007@gmail.com> <312bbba1-878c-5681-5e6c-b6de3f7feb55@kernel.dk> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [PATCH 2/8] io_uring: fix commit_cqring() locking in iopoll Message-ID: <63a8fab2-820f-d0c1-ad39-a3eb7af1d872@gmail.com> Date: Tue, 30 Jun 2020 18:00:43 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <312bbba1-878c-5681-5e6c-b6de3f7feb55@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 30/06/2020 17:46, Jens Axboe wrote: > On 6/30/20 8:36 AM, Pavel Begunkov wrote: >> On 30/06/2020 17:04, Jens Axboe wrote: >>> On 6/30/20 6:20 AM, Pavel Begunkov wrote: >>>> Don't call io_commit_cqring() without holding the completion spinlock >>>> in io_iopoll_complete(), it can race, e.g. with async request failing. >>> >>> Can you be more specific? >> >> io_iopoll_complete() >> -> io_req_free_batch() >> -> io_queue_next() >> -> io_req_task_queue() >> -> task_work_add() >> >> if this task_work_add() fails, it will be redirected to io-wq manager task >> to do io_req_task_cancel() -> commit_cqring(). >> >> >> And probably something similar will happen if a request currently in io-wq >> is retried with >> io_rw_should_retry() -> io_async_buf_func() -> task_work_add() > > For the IOPOLL setup, it should be protected by the ring mutex. Adding > the irq disable + lock for polling would be a nasty performance hit. Ok. For what it worth, it would be easier to accidentally screw in the future. I'll try it out. BTW, if you're going to cherry-pick patches from this series, just push them into the branch. I'll check git.kernel.dk later and resend what's left. -- Pavel Begunkov