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=-8.7 required=3.0 tests=BAYES_00,FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C1D17C433F5 for ; Thu, 9 Sep 2021 00:10:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5B5A610A3 for ; Thu, 9 Sep 2021 00:10:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244074AbhIIALh (ORCPT ); Wed, 8 Sep 2021 20:11:37 -0400 Received: from mail-il1-f197.google.com ([209.85.166.197]:42724 "EHLO mail-il1-f197.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348020AbhIIALh (ORCPT ); Wed, 8 Sep 2021 20:11:37 -0400 Received: by mail-il1-f197.google.com with SMTP id p10-20020a92d28a000000b0022b5f9140f7so146784ilp.9 for ; Wed, 08 Sep 2021 17:10:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=efoBqDBB90Zo6KBGwOvcOUmrPC3kWtBAO4+aYll1It8=; b=i8V1yzxXOgelW1uz8NbnAxCBDMQq4Se9Jid+NYBE+HnvCgOhtU96Wvn1h3FQ1AHsPr /G4xX6/34Wb2v5AE/icDIJDTk6oZQol3rYwpT62hybSORWJqcHEhxAlq2yihRg7gfTWH GM0tCueOwPRxy7XTVf5eosThawuh60KlOMGKl7DWpmafdptyCB9yPWXiZmMzgz6jcL8A Gg2JBIqY29DnovqJhjjFGNuGYhiWigUlCBF2RKe+nQieg7lxWnUU90FNTmkKp58Q8FH7 aNayAM18x4iTE4MjO9g00oNauB2QTbxgo2FrFT9giuW2G4SjU6ojttioNzHcC36dabYg Vx2w== X-Gm-Message-State: AOAM532EzWtualNANJBSztiS6vhilc4/LdESlJ2DPGOM5Uf90Jb5f9RS U4Jgub8EYxxBR+kVQCLNUcsZS9L4Fz/Hc4zpXod71ebC4KkE X-Google-Smtp-Source: ABdhPJz10IOR/DzL4piVzfvWlvIn/1eg9Ce7IdPfOkPYXWIzOOUWokUYnXL6+TYdlCFsSXl7dQtbpfiW5PEr1SbmuQucu7isb4+2 MIME-Version: 1.0 X-Received: by 2002:a02:9669:: with SMTP id c96mr192374jai.128.1631146228680; Wed, 08 Sep 2021 17:10:28 -0700 (PDT) Date: Wed, 08 Sep 2021 17:10:28 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000898c7405cb84d309@google.com> Subject: [syzbot] possible deadlock in io_sq_thread From: syzbot To: asml.silence@gmail.com, axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: a2b28235335f Merge branch 'dmi-for-linus' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=175ec47d300000 kernel config: https://syzkaller.appspot.com/x/.config?x=f5102874b5591af7 dashboard link: https://syzkaller.appspot.com/bug?extid=c9e7f2674197989e8afb compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c9e7f2674197989e8afb@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected 5.14.0-syzkaller #0 Not tainted ------------------------------------------------------ iou-sqp-17493/17496 is trying to acquire lock: ffff888084a320a8 (&ctx->uring_lock){+.+.}-{3:3}, at: __io_sq_thread fs/io_uring.c:7291 [inline] ffff888084a320a8 (&ctx->uring_lock){+.+.}-{3:3}, at: io_sq_thread+0x65a/0x1370 fs/io_uring.c:7368 but task is already holding lock: ffff888012986870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread+0x20f/0x1370 fs/io_uring.c:7356 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&sqd->lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 io_register_iowq_max_workers fs/io_uring.c:10551 [inline] __io_uring_register fs/io_uring.c:10757 [inline] __do_sys_io_uring_register+0x10aa/0x2e70 fs/io_uring.c:10792 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&ctx->uring_lock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 __io_sq_thread fs/io_uring.c:7291 [inline] io_sq_thread+0x65a/0x1370 fs/io_uring.c:7368 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sqd->lock); lock(&ctx->uring_lock); lock(&sqd->lock); lock(&ctx->uring_lock); *** DEADLOCK *** 1 lock held by iou-sqp-17493/17496: #0: ffff888012986870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread+0x20f/0x1370 fs/io_uring.c:7356 stack backtrace: CPU: 0 PID: 17496 Comm: iou-sqp-17493 Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 __io_sq_thread fs/io_uring.c:7291 [inline] io_sq_thread+0x65a/0x1370 fs/io_uring.c:7368 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.