INFO: task kworker/1:0:23 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:0 state:D stack:21296 pid:23 tgid:23 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x1325/0x47d0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383 rwsem_down_write_slowpath+0x4c2/0x12b0 kernel/locking/rwsem.c:1215 __down_write_common kernel/locking/rwsem.c:1347 [inline] __down_write kernel/locking/rwsem.c:1356 [inline] down_write+0x1c7/0x1f0 kernel/locking/rwsem.c:1632 kernfs_add_one+0x38/0xaa0 fs/kernfs/dir.c:825 kernfs_create_link+0x1a9/0x240 fs/kernfs/symlink.c:48 sysfs_do_create_link_sd+0x90/0x140 fs/sysfs/symlink.c:44 sysfs_do_create_link fs/sysfs/symlink.c:80 [inline] sysfs_create_link+0x61/0xc0 fs/sysfs/symlink.c:92 driver_sysfs_add+0x91/0x2d0 drivers/base/dd.c:489 really_probe+0x146/0xa60 drivers/base/dd.c:694 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x64/0x160 drivers/base/bus.c:620 device_add+0x121d/0x1970 drivers/base/core.c:3772 usb_new_device.cold+0x685/0x115c drivers/usb/core/hub.c:2698 hub_port_connect drivers/usb/core/hub.c:5570 [inline] hub_port_connect_change drivers/usb/core/hub.c:5710 [inline] port_event drivers/usb/core/hub.c:5874 [inline] hub_event+0x314d/0x4af0 drivers/usb/core/hub.c:5956 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x69a/0xc80 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: 5 locks held by kworker/0:1/11: 5 locks held by kworker/1:0/23: #0: ffff888106690540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc9000018fd18 ( (work_completion)(&hub->events) ){+.+.}-{0:0} , at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffff88810c3e41d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1102 [inline] #2: ffff88810c3e41d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bd/0x4af0 drivers/usb/core/hub.c:5902 #3: ffff888120bbc1d8 ( &dev->mutex ){....}-{4:4} , at: device_lock include/linux/device.h:1102 [inline] , at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073 #4: ffff888100e87980 (&root->kernfs_rwsem ){++++}-{4:4} , at: kernfs_add_one+0x38/0xaa0 fs/kernfs/dir.c:825 1 lock held by khungtaskd/29: #0: ffffffff896e2b40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] ffffffff896e2b40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] ffffffff896e2b40 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 2 locks held by kworker/u8:2/36: #0: ffff8881000ac140 ( (wq_completion)events_unbound ){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc90000267d18 ((work_completion)(&sub_info->work) ){+.+.}-{0:0} , at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 5 locks held by kworker/1:1/53: #0: ffff888106690540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc90000547d18 ( (work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffff88810bbf41d8 ( &dev->mutex ){....}-{4:4} , at: device_lock include/linux/device.h:1102 [inline] , at: hub_event+0x1bd/0x4af0 drivers/usb/core/hub.c:5902 #3: ffff888136a4d1d8 (&dev->mutex ){....}-{4:4} , at: device_lock include/linux/device.h:1102 [inline] , at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073 #4: ffff888100e87980 ( &root->kernfs_rwsem ){++++}-{4:4} , at: kernfs_add_one+0x38/0xaa0 fs/kernfs/dir.c:825 1 lock held by udevd/2855: #0: ffff888100e87980 ( &root->kernfs_rwsem ){++++}-{4:4}, at: kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 2 locks held by getty/2917: #0: ffff8881150da0a0 ( &tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc900000452e8 (&ldata->atomic_read_lock ){+.+.}-{4:4} , at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211 1 lock held by syz-executor/2971: #0: ffffffff896ee5e8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311 1 lock held by syz-executor/2975: #0: ffffffff896ee5e8 ( rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 4 locks held by udevd/5195: #0: ffff888120798e18 ( &p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 #1: ffff888123a79480 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165 #2: ffff8881361373c8 ( kn->active#26){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] kn->active#26){++++}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:166 #3: ffff888118db91d8 ( &dev->mutex ){....}-{4:4} , at: device_lock_interruptible include/linux/device.h:1107 [inline] , at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142 3 locks held by kworker/0:3/5232: 8 locks held by kworker/0:4/5248: 4 locks held by kworker/0:5/5264: 2 locks held by syz.3.368/6045: #0: ffff888100e87aa0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x49/0x120 fs/kernfs/dir.c:1791 #1: ffff888100e87980 ( &root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x51/0x120 fs/kernfs/dir.c:1792 2 locks held by syz.0.369/6047: #0: ffff888100e87aa0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x49/0x120 fs/kernfs/dir.c:1791 #1: ffff888100e87980 ( &root->kernfs_rwsem ){++++}-{4:4} , at: kernfs_remove_by_name_ns+0x51/0x120 fs/kernfs/dir.c:1792 3 locks held by syz.1.370/6051: #0: ffff88810bf00e00 ( &dev->mutex ){....}-{4:4} , at: device_lock include/linux/device.h:1102 [inline] , at: __device_driver_lock drivers/base/dd.c:1171 [inline] , at: __driver_attach+0x214/0x5b0 drivers/base/dd.c:1291 #1: ffff888100e87aa0 ( &root->kernfs_supers_rwsem ){++++}-{4:4} , at: kernfs_remove_by_name_ns+0x49/0x120 fs/kernfs/dir.c:1791 #2: ffff888100e87980 ( &root->kernfs_rwsem ){++++}-{4:4} , at: kernfs_remove_by_name_ns+0x51/0x120 fs/kernfs/dir.c:1792 3 locks held by syz.2.371/6050: #0: ffff88810bbfce00 (&dev->mutex ){....}-{4:4} , at: device_lock include/linux/device.h:1102 [inline] , at: __device_driver_lock drivers/base/dd.c:1171 [inline] , at: __driver_attach+0x214/0x5b0 drivers/base/dd.c:1291 #1: ffff888100e87aa0 ( &root->kernfs_supers_rwsem ){++++}-{4:4} , at: kernfs_remove_by_name_ns+0x49/0x120 fs/kernfs/dir.c:1791 #2: ffff888100e87980 ( &root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x51/0x120 fs/kernfs/dir.c:1792 1 lock held by syz-executor/6053: #0: ffff888100e87980 ( &root->kernfs_rwsem ){++++}-{4:4} , at: kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 1 lock held by syz-executor/6054: #0: ffff888100e87980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 1 lock held by syz-executor/6055: #0: ffff888100e87980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 1 lock held by syz-executor/6057: #0: ffff888100e87980 ( &root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 4 locks held by modprobe/6111: #0: ffff8881f57397a0 ( &rq->__lock ){-.-.}-{2:2} , at: raw_spin_rq_lock_nested kernel/sched/core.c:667 [inline] , at: raw_spin_rq_lock kernel/sched/sched.h:1653 [inline] , at: rq_lock kernel/sched/sched.h:1991 [inline] , at: __schedule+0x2dc/0x47d0 kernel/sched/core.c:7108 #1: ffff888102a81298 ( &sighand->siglock ){....}-{3:3} , at: do_notify_parent+0x78c/0x10b0 kernel/signal.c:2238 #2: ffff888101efcff8 ( &sig->wait_chldexit ){....}-{3:3} , at: __wake_up_common_lock kernel/sched/wait.c:124 [inline] , at: __wake_up_sync_key+0x1c/0x50 kernel/sched/wait.c:192 #3: ffff8881036f8a48 (&p->pi_lock){-.-.}-{2:2} , at: class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:571 [inline] , at: try_to_wake_up+0xbd/0x1580 kernel/sched/core.c:4292 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:122 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x141/0x190 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline] watchdog+0xcb1/0x1030 kernel/hung_task.c:561 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x69a/0xc80 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: yealink 3-1:36.0: urb_ctl_callback - urb status -71 NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5248 Comm: kworker/0:4 Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_power_efficient gc_worker RIP: 0010:io_serial_out+0x8f/0xb0 drivers/tty/serial/8250/8250_port.c:408 Code: 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 1c 66 03 5d 40 44 89 e8 89 da ee <5b> 5d 41 5c 41 5d e9 16 ed 52 04 e8 a1 f6 f0 fe eb a0 e8 2a f7 f0 RSP: 0018:ffffc900000074b8 EFLAGS: 00000002 RAX: 0000000000000020 RBX: 00000000000003f8 RCX: 0000000000000000 RDX: 00000000000003f8 RSI: ffffffff832b5a15 RDI: ffffffff94245da0 RBP: ffffffff94245d60 R08: 0000000000000001 R09: 000000000000001f R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000020 R14: ffffffff940868a1 R15: ffffffff832b59b0 FS: 0000000000000000(0000) GS:ffff88826863a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f39dbd5c028 CR3: 00000001168f8000 CR4: 00000000003506f0 Call Trace: serial_port_out include/linux/serial_core.h:813 [inline] serial8250_console_putchar drivers/tty/serial/8250/8250_port.c:3245 [inline] serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3307 [inline] serial8250_console_write+0xe2c/0x1a50 drivers/tty/serial/8250/8250_port.c:3385 console_emit_next_record kernel/printk/printk.c:3183 [inline] console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269 console_flush_all kernel/printk/printk.c:3343 [inline] __console_flush_and_unlock kernel/printk/printk.c:3373 [inline] console_unlock+0x103/0x260 kernel/printk/printk.c:3413 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479 dev_vprintk_emit+0x391/0x3e0 drivers/base/core.c:4996 dev_printk_emit+0xd2/0x10d drivers/base/core.c:5007 __dev_printk+0xcb/0x100 drivers/base/core.c:5019 _dev_err+0xef/0x127 drivers/base/core.c:5062 urb_ctl_callback.cold+0x41/0x8c drivers/input/misc/yealink.c:447 __usb_hcd_giveback_urb+0x38d/0x610 drivers/usb/core/hcd.c:1657 usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741 dummy_timer+0xda1/0x36c0 drivers/usb/gadget/udc/dummy_hcd.c:2005 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_run_softirq+0x17d/0x2c0 kernel/time/hrtimer.c:2113 handle_softirqs+0x1dd/0x990 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x160/0x210 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_is_held_type+0xf5/0x140 kernel/locking/lockdep.c:5945 Code: ff ff ff ff 65 0f c1 15 f9 48 83 05 83 fa 01 8b 44 24 04 75 2d 9c 5a 80 e6 02 75 47 41 f7 c5 00 02 00 00 74 01 fb 48 83 c4 08 <5b> 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc e9 17 ed 02 00 31 c0 RSP: 0018:ffffc900045afaa8 EFLAGS: 00000282 RAX: 0000000000000000 RBX: ffffffff896e2a80 RCX: 0000000000000001 RDX: 0000000000000046 RSI: ffffffff890d0880 RDI: ffffffff87b15380 RBP: ffff888119bcda00 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 00000000ffffffff R13: 0000000000000246 R14: ffff888119bce5a8 R15: 0000000000000002 lock_is_held include/linux/lockdep.h:249 [inline] __might_resched+0x29f/0x330 kernel/sched/core.c:9159 gc_worker+0xc77/0x1a30 net/netfilter/nf_conntrack_core.c:1610 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245