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=-3.7 required=3.0 tests=BAYES_00,FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0E48DC433E0 for ; Sun, 7 Mar 2021 09:50:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D888E65139 for ; Sun, 7 Mar 2021 09:50:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229753AbhCGJtn (ORCPT ); Sun, 7 Mar 2021 04:49:43 -0500 Received: from mail-io1-f70.google.com ([209.85.166.70]:46997 "EHLO mail-io1-f70.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229872AbhCGJtW (ORCPT ); Sun, 7 Mar 2021 04:49:22 -0500 Received: by mail-io1-f70.google.com with SMTP id w8so5334635iox.13 for ; Sun, 07 Mar 2021 01:49:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=V07qsaGEoHXexYmfa3BXedCZSaCtnYmBs8rqfZyeYlI=; b=ZBFIgURuL/xkuOSYY1LxNhOgaDDY9NZdqf/F/HAb8KPD8aIB3pbSCtLdX7eLVMKGjv Ijgp/2qUayuY23j2lW8a8jsta5QLuuQvgUrDQN5d/ZGJo2c6sQRkJtCMKpc9RGPACs7A ycK8i5uRKB8Rsu2qtyu+tfMjtXIoleOtqAoP3YUmW/0VUQ6Ob636AoTYhN8mhPvA6h+t BFAvgnJm4g5g+zv3LHf29vZXyFKISVnNBefzjmF7eVtv2RHy68P0Vpr+IeoFnkTLl0rs srQqjrBhh7kHoWO3YV/IKxRUJ8KQi9gCpQPU2Pr/Mtba7Mop3B6K1td1LcG65y6KZ7RO DzJA== X-Gm-Message-State: AOAM531++a6HBYyklK7TRRNAKLUngCvSNItF7WPu/OkLeu1Mjyd35gMp qwxv0Ftm8O3eJddNbrTpki7mTPozEsIwhqvw48kkOqtQUCdO X-Google-Smtp-Source: ABdhPJwkMgrO8DdTP9D02PdvTssCcIDOHdhMWUcL6D8tNcsYsyvMCXFxrbUITUzQjhzJDzcuxmb9r/VYn5+q4srYatU+tzgtMvom MIME-Version: 1.0 X-Received: by 2002:a02:1702:: with SMTP id 2mr18006148jah.43.1615110561007; Sun, 07 Mar 2021 01:49:21 -0800 (PST) Date: Sun, 07 Mar 2021 01:49:21 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000430bf505bcef3b00@google.com> Subject: [syzbot] possible deadlock in io_sq_thread_finish 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: linux-kernel@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: a38fd874 Linux 5.12-rc2 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=143ee02ad00000 kernel config: https://syzkaller.appspot.com/x/.config?x=db9c6adb4986f2f2 dashboard link: https://syzkaller.appspot.com/bug?extid=ac39856cb1b332dbbdda 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+ac39856cb1b332dbbdda@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected 5.12.0-rc2-syzkaller #0 Not tainted -------------------------------------------- kworker/u4:7/7615 is trying to acquire lock: ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_stop fs/io_uring.c:7099 [inline] ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_put_sq_data fs/io_uring.c:7115 [inline] ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_finish+0x408/0x650 fs/io_uring.c:7139 but task is already holding lock: ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park fs/io_uring.c:7088 [inline] ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park+0x63/0xc0 fs/io_uring.c:7082 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&sqd->lock); lock(&sqd->lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u4:7/7615: #0: ffff888010469138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888010469138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888010469138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888010469138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888010469138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888010469138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246 #1: ffffc900023a7da8 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250 #2: ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park fs/io_uring.c:7088 [inline] #2: ffff888144a02870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park+0x63/0xc0 fs/io_uring.c:7082 stack backtrace: CPU: 1 PID: 7615 Comm: kworker/u4:7 Not tainted 5.12.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound io_ring_exit_work Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_deadlock_bug kernel/locking/lockdep.c:2829 [inline] check_deadlock kernel/locking/lockdep.c:2872 [inline] validate_chain kernel/locking/lockdep.c:3661 [inline] __lock_acquire.cold+0x14c/0x3b4 kernel/locking/lockdep.c:4900 lock_acquire kernel/locking/lockdep.c:5510 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475 __mutex_lock_common kernel/locking/mutex.c:946 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1093 io_sq_thread_stop fs/io_uring.c:7099 [inline] io_put_sq_data fs/io_uring.c:7115 [inline] io_sq_thread_finish+0x408/0x650 fs/io_uring.c:7139 io_ring_ctx_free fs/io_uring.c:8408 [inline] io_ring_exit_work+0x82/0x9a0 fs/io_uring.c:8539 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 --- 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.