From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo2-f11.google.com (mail-oo2-f11.google.com [74.125.231.139]) (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 A886430F547 for ; Fri, 4 Sep 2026 14:03:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.139 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788530614; cv=none; b=VX2DvjUgoEzWNTaF5Sh/z5EnNHFdw2j6XQ8iRhWj5xhUA8O/AQFNPUq/CPsXFWndRvroskLDnvwUVm6JyX1PArYjbYl67df3Te1zaovqdTleoMKk3Ypi8SXQKmp202kZsl3+Mp97IyIpcDFm5SuIhpacAxDyqKOH0mol7Wx/ecM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788530614; c=relaxed/simple; bh=+drH4QyHQ/XiggDZTmWf+yyq+CRwT+qJ6dd2VDlHUa8=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=D9rnB4kuHthmvc5u7PXJwt727zBd32tUUZ159HmKcoj/lPkSUZHp++abQSAAJnYLbXyDPYr1Rp4lP+IDhInk0q6C38pH3Fycv2Z6MP08q3tvDPGmkf6Xq+ppoyogFRKl5fO8AGdsHr6sQEa24pLeBb99Z3/08NHVTre7/bGa9v0= 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=74.125.231.139 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-oo2-f11.google.com with SMTP id 46e09a7af769-7f4ddb9adf4so377944a34.1 for ; Fri, 04 Sep 2026 07:03:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788530611; x=1789135411; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=QFgKfa/2HgGsdHlMNRdxB+lo0N804UGlNZykqjVJ3O4=; b=UguQss1dqoz0Zv46jXCCVBEIR+NQWGs7TWYVwypCJRLtRNWc5N1XoKHoKmL5Bc01vr yc5Dd85HLrgiRqzb354jxbftqEVtohG0kGykPMm7kOtQ3RDpmu1fuTgXDv5048JPXZUb 3kaQtJY1jOK6cHoY8pBRkv8RCtnaXR2Xu7hHo/ZH+giiX8aAb80nVzbdUCMNhMgbQQgw SnuyWtKhMXf5hTwpWDg3/OY3+CsK8A5DFgIKYttSOKT4tYRthewJrexkLETf8ZK6BbNJ TM+WMmnTdjJlgvXqCyhfsnQj/yKJuPZbjcPBLbDMxNTqR5TpGBfBVKyq/tFwfymsxen/ OFZw== X-Forwarded-Encrypted: i=1; AKwUvBwmrA7AoIe5fyc72QnOZW+qhJAXuOi0ZL+bcIt3AITAX9oa4gc+oiUdGu9zRY5D/7JlvUYf8ZraGUyTR6A=@vger.kernel.org X-Gm-Message-State: AFuF++lIU0mEUXRkFaxgpna/X8UomGXY6IJVI/O7V+lfZs2OYYn6tvlw u9YE+1NgA80f4keAKTpKAMmV3/0q8C1efYSxIlgulU1FgxiV4W/adNpIPOGs50FyHyjNQFrmTP9 RvQe7dUU5Ux3TwJSEElS4jNgGqahU0uXXS6pEbdSgq1FAPdbi+RhwNpcwWZE= 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:c0d4:10b0:6b7:83c5:fe03 with SMTP id 006d021491bc7-6b783c60410mr1705118eaf.68.1788530611528; Fri, 04 Sep 2026 07:03:31 -0700 (PDT) Date: Fri, 04 Sep 2026 07:03:31 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a9acfb3.d07ac993.c20e9.0001.GAE@google.com> Subject: [syzbot] [usb?] INFO: task hung in usb_register_dev (3) From: syzbot To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 841e384b841a Merge tag 's390-7.3-2' of git://git.kernel.or.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=172c38f9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e dashboard link: https://syzkaller.appspot.com/bug?extid=3bc656a9271e7c8a5c6b compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=146828f9580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10ac38f9580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/c871e5c1ff29/disk-841e384b.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/056a12208699/vmlinux-841e384b.xz kernel image: https://storage.googleapis.com/syzbot-assets/09b9c08fc219/bzImage-841e384b.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3bc656a9271e7c8a5c6b@syzkaller.appspotmail.com INFO: task kworker/0:0:9 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:22984 pid:9 tgid:9 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7270 __schedule_loop kernel/sched/core.c:7347 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7362 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419 rwsem_down_write_slowpath+0x87d/0x1080 kernel/locking/rwsem.c:1215 __down_write_common kernel/locking/rwsem.c:1347 [inline] __down_write kernel/locking/rwsem.c:1356 [inline] down_write+0x1bc/0x200 kernel/locking/rwsem.c:1632 usb_register_dev+0x142/0x5e0 drivers/usb/core/file.c:134 sisusb_probe+0x1f9/0xf00 drivers/usb/misc/sisusbvga/sisusbvga.c:2816 usb_probe_interface+0x788/0xe50 drivers/usb/core/driver.c:399 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c4/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12a/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3776 usb_set_configuration+0x1ad8/0x2180 drivers/usb/core/message.c:2268 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250 usb_probe_device+0x1c3/0x3b0 drivers/usb/core/driver.c:293 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c4/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12a/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3776 usb_new_device+0x9aa/0x1690 drivers/usb/core/hub.c:2708 hub_port_connect drivers/usb/core/hub.c:5580 [inline] hub_port_connect_change drivers/usb/core/hub.c:5720 [inline] port_event drivers/usb/core/hub.c:5884 [inline] hub_event+0x28e8/0x4d30 drivers/usb/core/hub.c:5966 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 INFO: task kworker/0:2:988 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:2 state:D stack:21800 pid:988 tgid:988 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7270 __schedule_loop kernel/sched/core.c:7347 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7362 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419 rwsem_down_write_slowpath+0x87d/0x1080 kernel/locking/rwsem.c:1215 __down_write_common kernel/locking/rwsem.c:1347 [inline] __down_write kernel/locking/rwsem.c:1356 [inline] down_write+0x1bc/0x200 kernel/locking/rwsem.c:1632 usb_register_dev+0x142/0x5e0 drivers/usb/core/file.c:134 sisusb_probe+0x1f9/0xf00 drivers/usb/misc/sisusbvga/sisusbvga.c:2816 usb_probe_interface+0x788/0xe50 drivers/usb/core/driver.c:399 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c4/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12a/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3776 usb_set_configuration+0x1ad8/0x2180 drivers/usb/core/message.c:2268 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250 usb_probe_device+0x1c3/0x3b0 drivers/usb/core/driver.c:293 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c4/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12a/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3776 usb_new_device+0x9aa/0x1690 drivers/usb/core/hub.c:2708 hub_port_connect drivers/usb/core/hub.c:5580 [inline] hub_port_connect_change drivers/usb/core/hub.c:5720 [inline] port_event drivers/usb/core/hub.c:5884 [inline] hub_event+0x28e8/0x4d30 drivers/usb/core/hub.c:5966 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 INFO: task kworker/1:5:5648 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:5 state:D stack:22416 pid:5648 tgid:5648 ppid:2 task_flags:0x4288060 flags:0x00080000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7270 __schedule_loop kernel/sched/core.c:7347 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7362 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419 rwsem_down_write_slowpath+0x87d/0x1080 kernel/locking/rwsem.c:1215 __down_write_common kernel/locking/rwsem.c:1347 [inline] __down_write kernel/locking/rwsem.c:1356 [inline] down_write+0x1bc/0x200 kernel/locking/rwsem.c:1632 usb_deregister_dev+0x87/0x240 drivers/usb/core/file.c:186 sisusb_disconnect+0x59/0x220 drivers/usb/misc/sisusbvga/sisusbvga.c:2921 usb_unbind_interface+0x295/0x9f0 drivers/usb/core/driver.c:461 device_remove drivers/base/dd.c:618 [inline] __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x4f5/0x880 drivers/base/dd.c:1372 bus_remove_device+0x444/0x560 drivers/base/bus.c:664 device_del+0x524/0x8f0 drivers/base/core.c:3965 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2350 hub_port_connect drivers/usb/core/hub.c:5420 [inline] hub_port_connect_change drivers/usb/core/hub.c:5720 [inline] port_event drivers/usb/core/hub.c:5884 [inline] hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5966 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Showing all locks held in the system: locks held by kworker/0:0/9: 6, on CPU#0: #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc900000e7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc900000e7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc900000e7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc900000e7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffff88802944a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #2: ffff88802944a1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912 #3: ffff88802aa761d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #3: ffff88802aa761d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #4: ffff88807c95c1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #4: ffff88807c95c1a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #5: ffffffff8fb05228 (minor_rwsem#2){++++}-{4:4}, at: usb_register_dev+0x142/0x5e0 drivers/usb/core/file.c:134 locks held by pr/ttyS0/16: 2, last CPU#0: #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline] #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline] #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291 #1: ffffffff9ad32098 (&port_lock_key){-.-.}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline] #1: ffffffff9ad32098 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0 drivers/tty/serial/8250/8250_core.c:413 locks held by kworker/1:1/30: 6, on CPU#1: #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc90000a67c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90000a67c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90000a67c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc90000a67c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffff8880294ff1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #2: ffff8880294ff1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912 #3: ffff88801ff2a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #3: ffff88801ff2a1d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0 drivers/usb/core/hub.c:2341 #4: ffff88807f18f1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #4: ffff88807f18f1a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline] #4: ffff88807f18f1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369 #5: ffffffff8fb05228 (minor_rwsem#2){++++}-{4:4}, at: usb_deregister_dev+0x87/0x240 drivers/usb/core/file.c:186 locks held by khungtaskd/32: 1, last CPU#1: #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6837 locks held by kworker/0:2/988: 6, on CPU#0: #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc900049ffc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc900049ffc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc900049ffc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc900049ffc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffff8880294d01d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #2: ffff8880294d01d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912 #3: ffff88802aa121d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #3: ffff88802aa121d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #4: ffff88807c95b1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #4: ffff88807c95b1a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #5: ffffffff8fb05228 (minor_rwsem#2){++++}-{4:4}, at: usb_register_dev+0x142/0x5e0 drivers/usb/core/file.c:134 locks held by getty/5368: 2, on CPU#1: #0: ffff8880324e50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211 locks held by udevd/5647: 4, on CPU#0: #0: ffff8880777adf38 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0 fs/seq_file.c:183 #1: ffff888035d73080 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5d/0x420 fs/kernfs/file.c:165 #2: ffff8880351195a8 (kn->active#30){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] #2: ffff8880351195a8 (kn->active#30){.+.+}-{0:0}, at: kernfs_seq_start+0xb2/0x420 fs/kernfs/file.c:166 #3: ffff88802aa121d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline] #3: ffff88802aa121d8 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142 locks held by kworker/1:5/5648: 6, on CPU#1: #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801fafe940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc90003affc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90003affc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90003affc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc90003affc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffff8880292c41d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #2: ffff8880292c41d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912 #3: ffff8880258e41d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #3: ffff8880258e41d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0 drivers/usb/core/hub.c:2341 #4: ffff888029d911a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #4: ffff888029d911a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline] #4: ffff888029d911a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369 #5: ffffffff8fb05228 (minor_rwsem#2){++++}-{4:4}, at: usb_deregister_dev+0x87/0x240 drivers/usb/core/file.c:186 locks held by udevd/5649: 4, on CPU#0: #0: ffff88802812b098 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0 fs/seq_file.c:183 #1: ffff888035440480 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5d/0x420 fs/kernfs/file.c:165 #2: ffff8880343120f8 (kn->active#30){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] #2: ffff8880343120f8 (kn->active#30){.+.+}-{0:0}, at: kernfs_seq_start+0xb2/0x420 fs/kernfs/file.c:166 #3: ffff88802aa761d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline] #3: ffff88802aa761d8 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142 locks held by syz-executor284/5651: 2, on CPU#1: #0: ffffffff8fb05228 (minor_rwsem#2){++++}-{4:4}, at: usb_open+0x30/0x1e0 drivers/usb/core/file.c:38 #1: ffff8880362758c8 (&(sisusb->lock)){+.+.}-{4:4}, at: sisusb_open+0x96/0x420 drivers/usb/misc/sisusbvga/sisusbvga.c:2213 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline] watchdog+0xfd7/0x1030 kernel/hung_task.c:561 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 16 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:delay_tsc+0x5d/0xd0 arch/x86/lib/delay.c:77 Code: 89 d7 49 c1 e7 20 49 09 c7 4d 29 f7 49 39 df 73 55 bf 01 00 00 00 e8 52 06 b2 f5 65 48 8b 05 fa 98 b1 07 48 85 c0 74 1c f3 90 01 00 00 00 e8 e9 04 b2 f5 e8 84 7a 01 00 39 c5 75 0e 0f 01 f9 RSP: 0018:ffffc900001578b8 EFLAGS: 00000082 RAX: 8000000000000001 RBX: 0000000000000899 RCX: ffffffff9a9db501 RDX: 0000000000000001 RSI: ffffffff8c6d9460 RDI: 00000000ffffffff RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff8be2d6c0 R12: 1ffffffff35a646d R13: 00000000ffffffff R14: 00000083c2e0b525 R15: 00000000000000e5 FS: 0000000000000000(0000) GS:ffff888124cd9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f07aeae3640 CR3: 00000000707d6000 CR4: 00000000003526f0 Call Trace: udelay include/asm-generic/delay.h:62 [inline] wait_for_lsr+0x147/0x2f0 drivers/tty/serial/8250/8250_port.c:2019 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline] __serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3345 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline] __serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline] serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3493 nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1 nbcon_emit_one kernel/printk/nbcon.c:1157 [inline] nbcon_kthread_func+0x679/0x880 kernel/printk/nbcon.c:1271 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- 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. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup