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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 DE5CFC388F9 for ; Sat, 7 Nov 2020 20:06:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 745892087E for ; Sat, 7 Nov 2020 20:06:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="epHyPV6G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725846AbgKGUGN (ORCPT ); Sat, 7 Nov 2020 15:06:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725836AbgKGUGN (ORCPT ); Sat, 7 Nov 2020 15:06:13 -0500 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E3A6C0613CF for ; Sat, 7 Nov 2020 12:06:13 -0800 (PST) Received: by mail-wr1-x431.google.com with SMTP id p8so3955550wrx.5 for ; Sat, 07 Nov 2020 12:06:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:references:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=WHBfg6jH7ngncxBG92qVkyIfo08y9p1DkJ6IBq47stE=; b=epHyPV6G3bPbvbWGMEsZC2d+At9UYaY+M5TGPH0xZKd50R+fybmLTkuv9bAbNKSh/q G1anYZ+JsWMz6HnGpFDj3llKMj7C8dMZC4BfUBhvMn9qOq8Qkvugm4FndceMNEFhDAvH LXSxFwpnz9ma8bu9nbnQvd/VzuAr00RENalAiZ9cR/TlPjFGRKwFF54SUs2IxeWXya0E KvEqOfavUZVn5v1e6l6JNomXYLzob4oEaoPQCB0MBHgoWWuf0LKA2ZHTvPNwV58oqI1F IOynDl916EwR66yTDQm5fmL3dG4pCoy8WM6MSkuGtOK9I8bCEKVIBrRfmeaKo0Fuwi5e xUCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=WHBfg6jH7ngncxBG92qVkyIfo08y9p1DkJ6IBq47stE=; b=cHzqjZmBHXqM5KHE5BnR1NpV/lWpJHZsqvS7gyDUuAHRIDXqXTNOCpT5d1xf9SexkF ljL9wzWAKTaaa+8iOuMD7IJ2kkrp8nWdlH8PaGMm2209J1OLbQSbbLvwEti7EdG/cIR+ ncXRJpgCQf+H4RSQBnBmPXDmkc6lL3YpUiXe7MTKV3h4d/1TD/dFPlBtWcta/10/kSoe idpoy5YmymlchU8GAa+nUlwfJCxor5ioUBZ7IH9KPjRQEoIe0HXblDB5BmYDgPCEVq9F ZwXMegM3Rq2DAaYPVlfgWDMVBSyqCv7Ka1q8cy1mDn9LRjVkdEkx1xt/+eQmAJ+x0J9x y3Gg== X-Gm-Message-State: AOAM530+SjClmN0lPDWlKfaS/OEc1lrIEi9W+8L0hzmu3Q1kzMCh9lF6 DyJe46Npe5Ydm1VOGv2nf1k= X-Google-Smtp-Source: ABdhPJxdhZnZ9b/HaVFE4t8+Y/udZhTDSn+fwTE2/gkiOMlvuOc0SjdI4cF6AVYRmBk32se9/LNDKw== X-Received: by 2002:adf:bb43:: with SMTP id x3mr9444198wrg.250.1604779571857; Sat, 07 Nov 2020 12:06:11 -0800 (PST) Received: from [192.168.1.84] (host109-152-100-164.range109-152.btcentralplus.com. [109.152.100.164]) by smtp.gmail.com with ESMTPSA id r10sm7377575wmg.16.2020.11.07.12.06.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 07 Nov 2020 12:06:11 -0800 (PST) Subject: Re: Using SQPOLL for-5.11/io_uring kernel NULL pointer dereference From: Pavel Begunkov To: Josef , io-uring , Jens Axboe Cc: norman@apache.org References: <69f14eaa-b75d-8f7b-3897-1f47bb2e325b@gmail.com> 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== Message-ID: <1a4e38df-d977-abea-e6b8-b64f436c81a5@gmail.com> Date: Sat, 7 Nov 2020 20:03:08 +0000 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: <69f14eaa-b75d-8f7b-3897-1f47bb2e325b@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 07/11/2020 16:28, Pavel Begunkov wrote: > On 07/11/2020 14:09, Josef wrote: >>> I haven't got the first email, is it "kernel NULL pointer dereference" >>> as in the subject or just freeze? >> >> that's weird..probably the size of the attached log file is too big... >> here dmesg log file >> https://gist.github.com/1Jo1/3d0bcefc18f097265f0dc1ef054a87c0 > > That's much better with the log, thanks! I'll take a look later Ok, we get into fget_many() without ->files, and it's clear how it may happen. I'll write up a patch. > >> >>> - did you locate which test hangs it? If so what it uses? e.g. SQPOLL >>> sharing, IOPOLL., etc. >> >> yes, it uses SQPOLL, without sharing, IPOLL is not enabled, and Async >> Flag is enabled >> >>> - is it send/recvmsg, send/recv you use? any other? >> >> no the tests which occurs the error use these operations: OP_READ, >> OP_WRITE, OP_POLL_ADD, OP_POLL_REMOVE, OP_CLOSE, OP_ACCEPT, OP_TIMEOUT >> (OP_READ, OP_WRITE and OP_CLOSE async flag is enabled) >> >>> - does this happen often? >> >> yeah quite often >> >>> - you may try `funcgraph __io_sq_thread -H` or even with `io_sq_thread` >>> (funcgraph is from bpftools). Or catch that with some other tools. >> >> I'm not quite familiar with these tools( kernel debugging in general) >> I'll take a look tomorrow > -- Pavel Begunkov