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=-9.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 88C66C433ED for ; Thu, 13 May 2021 21:29:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6385C613C3 for ; Thu, 13 May 2021 21:29:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233505AbhEMVaQ (ORCPT ); Thu, 13 May 2021 17:30:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233421AbhEMVaO (ORCPT ); Thu, 13 May 2021 17:30:14 -0400 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [IPv6:2a00:1450:4864:20::32c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0D91C061574; Thu, 13 May 2021 14:29:04 -0700 (PDT) Received: by mail-wm1-x32c.google.com with SMTP id o6-20020a05600c4fc6b029015ec06d5269so526065wmq.0; Thu, 13 May 2021 14:29:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:references:from:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=z8BiVhBFJw9B5XZbvfu0NghJzv585Oe1VKPpDiAFKuo=; b=RomoLTlvyitqrerTbZ8f3VrcOHVKg8woQxVVFYn+tvJDgXW3PfzW/pRTpiwoLRvwBR p0KXy6ik4Y4Kw8A/Z58zlzWZITnTQ3gAAh/sfL9HRi7oimPmp9WP69R2YpNpW9WZeUqS bWrSF7aPLJasplqY1e37cSJTFDP2bMxoRp9k2pUNlAF3a7vj2kbA3fLeideTl6N+2jVe FNvzGtQC2LHFySzqsxgwNg97x/STLDE8eCaKSq5Xwg7PJ1JcJ8YiGlkdbnld4wz0lOGu nH8JUDh8rjAn4VaX25RYDFtKRBRQOTjf4CXxo8w8yNAigS6NF0NJ3L6zq0XVfRfFj5g1 xajQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:subject:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=z8BiVhBFJw9B5XZbvfu0NghJzv585Oe1VKPpDiAFKuo=; b=rS7+PIATKu5PDS9St3ltJCPGc0iEKm6QSK8Vtb4s/fP9mIIv/eOB5aVuFALUV2q7wt uYLl/aJQdJFOQKVs1ozlNbFgVfLq7kIp2QvxCsU+Y6ZLsiiI7/XJc8U0P+zzi4J9+2Vb 3BB1LSRCo5x2TKaPXlzXTU82f7QQMcMt/UQPnG9M+KQwc4n5gDAjj99WZwCKnGD7rdGp 3lQQNQI6rLzZtx0Fwm3RAvBmLK8g2FQeTZcxDo+iuqDcwiiOaCaQFiR9ZkoDwgOKdM3M 4Fq5LIvrThfmFEJun2QmLgmDuTtjvYteKX5mIVnhaQi2yDCNf2tLLFK8LgZJq1Sp/wGB NG7g== X-Gm-Message-State: AOAM531tqQAd7h1bKcWY75RdhY1vsN4zAzT/MZFzaBzLnyKhiyeIdL4w qBPdeC8c7fhXK1cdCDPOUWw= X-Google-Smtp-Source: ABdhPJyygvlMjkgoy0N2dAiMO4Ogg5+kAKmQdP/X/tOKPdhnWjRF88iRjbgKqEbL+TuoBeg0/A34VQ== X-Received: by 2002:a1c:a706:: with SMTP id q6mr4204494wme.71.1620941343368; Thu, 13 May 2021 14:29:03 -0700 (PDT) Received: from [192.168.8.197] ([148.252.132.196]) by smtp.gmail.com with ESMTPSA id k11sm9444777wmj.1.2021.05.13.14.29.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 May 2021 14:29:02 -0700 (PDT) To: Palash Oswal Cc: Jens Axboe , io-uring@vger.kernel.org, LKML , syzbot+11bf59db879676f59e52@syzkaller.appspotmail.com References: <0000000000000c97e505bdd1d60e@google.com> <53a22ab4-7a2d-4ebd-802d-9d1b4ce4e087n@googlegroups.com> From: Pavel Begunkov Subject: Re: INFO: task hung in io_uring_cancel_sqpoll Message-ID: <4127fb94-89d2-4e36-8835-514118cb1cce@gmail.com> Date: Thu, 13 May 2021 22:28:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/10/21 5:47 AM, Palash Oswal wrote: > On Mon, May 3, 2021 at 4:15 PM Pavel Begunkov > wrote: > >> On 5/3/21 5:41 AM, Palash Oswal wrote: >>> On Mon, May 3, 2021 at 3:42 AM Pavel Begunkov >> wrote: >>>> The test might be very useful. Would you send a patch to >>>> liburing? Or mind the repro being taken as a test? >>> >>> Pavel, >>> >>> I'm working on a PR for liburing with this test. Do you know how I can >> >> Perfect, thanks >> >>> address this behavior? >> >> As the hang is sqpoll cancellations, it's most probably >> fixed in 5.13 + again awaits to be taken for stable. >> >> Don't know about segfaults, but it was so for long, and >> syz reproducers are ofthen faults for me, and exit with 0 >> in the end. So, I wouldn't worry about it. >> >> > Hey Pavel, > The bug actually fails to reproduce on 5.12 when the fork() call is made by > the runtests.sh script. This causes the program to end correctly, and the > hang does not occur. I verified this on 5.12 where the bug isn't patched. > Just running the `sqpoll-cancel-hang` triggers the bug; whereas running it > after being forked from runtests.sh does not trigger the bug. I see. fyi, it's always good to wait for 5 minutes, because some useful logs are not generated immediately but do timeout based hang detection. I'd think that may be due CLONE_IO and how to whom it binds workers, but can you try first: 1) timeout -s INT -k $TIMEOUT $TIMEOUT ./sqpoll-cancel-hang 2) remove timeout from /tests/Makefile and run "./runtests.sh sqpoll-cancel-hang" again looking for faults? diff --git a/test/runtests.sh b/test/runtests.sh index e8f4ae5..2b51dca 100755 --- a/test/runtests.sh +++ b/test/runtests.sh @@ -91,7 +91,8 @@ run_test() fi # Run the test - timeout -s INT -k $TIMEOUT $TIMEOUT ./$test_name $dev + # timeout -s INT -k $TIMEOUT $TIMEOUT ./$test_name $dev + ./$test_name $dev local status=$? # Check test status > > The segfaults are benign, but notice the "All tests passed" in the previous > mail. It should not have passed, as the run was on 5.12. Therefore I wanted > to ask your input on how to address this odd behaviour, where the > involvement of runtests.sh actually mitigated the bug. > > > >>> root@syzkaller:~/liburing/test# ./runtests.sh sqpoll-cancel-hang >>> Running test sqp[ 15.310997] Running test sqpoll-cancel-hang: >>> oll-cancel-hang: >>> [ 15.333348] sqpoll-cancel-h[305]: segfault at 0 ip 000055ad00e265e3 >> sp] >>> [ 15.334940] Code: 89 d8 8d 34 90 8b 45 04 ba 03 00 00 00 c1 e0 04 03 >> 46 >>> All tests passed >>> >>> root@syzkaller:~/liburing/test# ./sqpoll-cancel-hang >>> [ 13.572639] sqpoll-cancel-h[298]: segfault at 0 ip 00005634c4a455e3 >> sp] >>> [ 13.576506] Code: 89 d8 8d 34 90 8b 45 04 ba 03 00 00 00 c1 e0 04 03 >> 46 >>> [ 23.350459] random: crng init done >>> [ 23.352837] random: 7 urandom warning(s) missed due to ratelimiting >>> [ 243.090865] INFO: task iou-sqp-298:299 blocked for more than 120 >> secon. >>> [ 243.095187] Not tainted 5.12.0 #142 >>> [ 243.099800] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" >> disable. >>> [ 243.105928] task:iou-sqp-298 state:D stack: 0 pid: 299 ppid: >> 4 >>> [ 243.111044] Call Trace: >>> [ 243.112855] __schedule+0xb1d/0x1130 >>> [ 243.115549] ? __sched_text_start+0x8/0x8 >>> [ 243.118328] ? io_wq_worker_sleeping+0x145/0x500 >>> [ 243.121790] schedule+0x131/0x1c0 >>> [ 243.123698] io_uring_cancel_sqpoll+0x288/0x350 >>> [ 243.125977] ? io_sq_thread_unpark+0xd0/0xd0 >>> [ 243.128966] ? mutex_lock+0xbb/0x130 >>> [ 243.132572] ? init_wait_entry+0xe0/0xe0 >>> [ 243.135429] ? wait_for_completion_killable_timeout+0x20/0x20 >>> [ 243.138303] io_sq_thread+0x174c/0x18c0 >>> [ 243.140162] ? io_rsrc_put_work+0x380/0x380 >>> [ 243.141613] ? init_wait_entry+0xe0/0xe0 >>> [ 243.143686] ? _raw_spin_lock_irq+0xa5/0x180 >>> [ 243.145619] ? _raw_spin_lock_irqsave+0x190/0x190 >>> [ 243.147671] ? calculate_sigpending+0x6b/0xa0 >>> [ 243.149036] ? io_rsrc_put_work+0x380/0x380 >>> [ 243.150694] ret_from_fork+0x22/0x30 >>> >>> Palash >>> >> >> -- >> Pavel Begunkov >> > -- Pavel Begunkov