From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f69.google.com (mail-oo1-f69.google.com [209.85.161.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 79CA0329E62 for ; Fri, 20 Feb 2026 16:41:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771605695; cv=none; b=J4cvw9mZI69nrU4lJn4xUOYYXN3CGym+DdwxO5U/D6edqswzdzN8YCDj6Mj/9gvKVeVyhvNg8YwxEuP3fVKOPTDQeOxyaX8LMBhool/XauFJhn68Nnuu+dRXHjvSIGh8LiOpxdAG2bw9yvOchFxQinufH2y+Nuh337glWail7uw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771605695; c=relaxed/simple; bh=jdEtbseSAU80wMGx3pobYkx8kz+4fYwWQAhTpdx0WN0=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=j2AX7Ww89HAW9TZRMAJH6AMDFsvr20mey+XP0CebQI8CQi35YcM723Z5IOKHfi3TC9dBulyJF3CnOhEdCU/Pxn3s0F9fMkFWdkSLyrPES1h4FmaKvFWf+fGsVUSMtQQQqyowx3lYI7KwUHlvjaklY4CTdk4MCKpS0Ii4qf+GRtU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.161.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo1-f69.google.com with SMTP id 006d021491bc7-679c448d15cso2734805eaf.3 for ; Fri, 20 Feb 2026 08:41:33 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771605692; x=1772210492; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=7d6c9bahc0ejx4mmEL/Ki4rA2jNXSkvOpRRwr5hI4MQ=; b=xG/QwQ6Amk06stQejCV7V/qYzAW1EhN+BLME3HnNz36sUl7IBYRc1geQ5v9Z9V4flM b09oc5YDdia8BHLoWb42n/m3BBWyFZ4tc1qpKA11uJ4hpt5ggeZPuUQz3XZWpBVoyxA6 kl1MzPwopsJolDgv+hx++1rU8mcVL8o0mNNzBmn3xY17NCAO6GBZFXyjuDsk/8cOHgj3 /IpjuOAFVFZ/8JcKIACoJS5pxI88B5wFV9S8gVrMsuY8SQRfQRmAs3DcC51MYbwPEgB3 xo15z50a9KArydah8I4LOlO9NopDscM6kmNpgpCVt50s0XhZWwl0V1ko4iqzKR4Fd83Z la4w== X-Forwarded-Encrypted: i=1; AJvYcCUWxED1oTUpqy7MeNOA5e52aF8YWtc+yXepcvRaRTuc8MJrTohuofYNGdEVYu4tDdFrpfmRIBB4KSBdNy8=@vger.kernel.org X-Gm-Message-State: AOJu0YzOAVvh0ikJBaf5KVN37zprPlPtpaK/Avjg0kBnHW6pQOIURmMD XGM394WhKzWh2Uetts7xvdjgZDemzz70rqu4qGjaFTCDNPPRGz6c+jKhfl2HxLgEWY3zFyZETy1 uHXOCS5o8L7qlUbIw45blmsUqrx0Z1616gbGON7Xte84xtdN9aDielF8A4QU= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1792:b0:676:e8d1:bb57 with SMTP id 006d021491bc7-679c44ebd39mr277572eaf.58.1771605692423; Fri, 20 Feb 2026 08:41:32 -0800 (PST) Date: Fri, 20 Feb 2026 08:41:32 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69988ebc.a70a0220.2c38d7.0142.GAE@google.com> Subject: [syzbot] [kernel?] possible deadlock in worker_thread (3) From: syzbot To: bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, tglx@kernel.org, x86@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 635c467cc14e Add linux-next specific files for 20260213 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=15339b3a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=61690c38d1398936 dashboard link: https://syzkaller.appspot.com/bug?extid=0b6ec149bb8b98bd9485 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/78b3d15ca8e6/disk-635c467c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/a95f3d108ef4/vmlinux-635c467c.xz kernel image: https://storage.googleapis.com/syzbot-assets/e58086838b24/bzImage-635c467c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+0b6ec149bb8b98bd9485@syzkaller.appspotmail.com block nbd1: Receive control failed (result -32) ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kworker/u9:3/5827 is trying to acquire lock: ffff8880275b9a78 (&nbd->config_lock){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 but task is already holding lock: ffffc90003bd7c40 ((work_completion)(&args->work)#3){+.+.}-{0:0}, at: process_one_work+0x87c/0x1650 kernel/workqueue.c:3255 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((work_completion)(&args->work)#3){+.+.}-{0:0}: process_one_work+0x895/0x1650 kernel/workqueue.c:3255 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 ((wq_completion)nbd3-recv){+.+.}-{0:0}: touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:3994 __flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:4036 nbd_disconnect_and_put+0x9e/0x2c0 drivers/block/nbd.c:2264 nbd_genl_disconnect+0x4a9/0x590 drivers/block/nbd.c:2303 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x18f/0x1d0 net/socket.c:737 __sock_sendmsg net/socket.c:752 [inline] ____sys_sendmsg+0x589/0x8c0 net/socket.c:2610 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2664 __sys_sendmsg net/socket.c:2696 [inline] __do_sys_sendmsg net/socket.c:2701 [inline] __se_sys_sendmsg net/socket.c:2699 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2699 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&nbd->config_lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 nbd_config_put+0x2c/0x580 drivers/block/nbd.c:1434 recv_work+0x1cc1/0x1d90 drivers/block/nbd.c:1026 process_one_work+0x949/0x1650 kernel/workqueue.c:3279 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: &nbd->config_lock --> (wq_completion)nbd3-recv --> (work_completion)(&args->work)#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&args->work)#3); lock((wq_completion)nbd3-recv); lock((work_completion)(&args->work)#3); lock(&nbd->config_lock); *** DEADLOCK *** 2 locks held by kworker/u9:3/5827: #0: ffff8880275c9148 ((wq_completion)nbd1-recv){+.+.}-{0:0}, at: process_one_work+0x855/0x1650 kernel/workqueue.c:3254 #1: ffffc90003bd7c40 ((work_completion)(&args->work)#3){+.+.}-{0:0}, at: process_one_work+0x87c/0x1650 kernel/workqueue.c:3255 stack backtrace: CPU: 0 UID: 0 PID: 5827 Comm: kworker/u9:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: nbd1-recv recv_work Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776 refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 nbd_config_put+0x2c/0x580 drivers/block/nbd.c:1434 recv_work+0x1cc1/0x1d90 drivers/block/nbd.c:1026 process_one_work+0x949/0x1650 kernel/workqueue.c:3279 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 kthread+0x388/0x470 kernel/kthread.c:467 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 block nbd1: shutting down sockets --- This report is generated by a bot. 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