INFO: task kworker/1:8:4394 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:8     state:D stack:21136 pid:4394  ppid:2      flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6698
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x548/0xae0 kernel/locking/mutex.c:747
 usb_audio_probe+0x3e7/0x1e70 sound/usb/card.c:812
 usb_probe_interface+0x5be/0xae0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x24a/0xb40 drivers/base/dd.c:638
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
 __device_attach_driver+0x2c6/0x510 drivers/base/dd.c:962
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a7/0x480 drivers/base/dd.c:1034
 bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
 device_add+0xbcf/0x1050 drivers/base/core.c:3712
 usb_set_configuration+0x19d5/0x2030 drivers/usb/core/message.c:2223
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x126/0x250 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x24a/0xb40 drivers/base/dd.c:638
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
 __device_attach_driver+0x2c6/0x510 drivers/base/dd.c:962
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a7/0x480 drivers/base/dd.c:1034
 bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
 device_add+0xbcf/0x1050 drivers/base/core.c:3712
 usb_new_device+0xa01/0x15e0 drivers/usb/core/hub.c:2664
 hub_port_connect drivers/usb/core/hub.c:5522 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5662 [inline]
 port_event drivers/usb/core/hub.c:5822 [inline]
 hub_event+0x2b2f/0x5200 drivers/usb/core/hub.c:5904
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e5b0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2edd0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2dc20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2dc20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2dc20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
2 locks held by udevd/3638:
2 locks held by getty/4024:
 #0: ffff88802f7ea098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
6 locks held by kworker/1:8/4394:
 #0: ffff88801becd538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000456fd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff88814634e190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #2: ffff88814634e190 (&dev->mutex){....}-{3:3}, at: hub_event+0x178/0x5200 drivers/usb/core/hub.c:5850
 #3: ffff88807bf15190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #3: ffff88807bf15190 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x480 drivers/base/dd.c:1009
 #4: ffff88807bf16118 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #4: ffff88807bf16118 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x480 drivers/base/dd.c:1009
 #5: ffffffff8dd016a8 (register_mutex#6){+.+.}-{3:3}, at: usb_audio_probe+0x3e7/0x1e70 sound/usb/card.c:812
7 locks held by syz.5.4227/18653:
 #0: ffff888027da1190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #0: ffff888027da1190 (&dev->mutex){....}-{3:3}, at: usbdev_do_ioctl drivers/usb/core/devio.c:2609 [inline]
 #0: ffff888027da1190 (&dev->mutex){....}-{3:3}, at: usbdev_ioctl+0x143/0x1f20 drivers/usb/core/devio.c:2817
 #1: ffff888059852118 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #1: ffff888059852118 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1099 [inline]
 #1: ffff888059852118 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb1/0x7c0 drivers/base/dd.c:1302
 #2: ffff8880268d5190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #2: ffff8880268d5190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0xf8/0x8a0 drivers/usb/core/hub.c:2310
 #3: ffff8880268d4118 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #3: ffff8880268d4118 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1099 [inline]
 #3: ffff8880268d4118 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb1/0x7c0 drivers/base/dd.c:1302
 #4: ffffffff8dd016a8 (register_mutex#6){+.+.}-{3:3}, at: usb_audio_disconnect+0xd0/0x6f0 sound/usb/card.c:960
 #5: ffff8880606ce170 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #5: ffff8880606ce170 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1099 [inline]
 #5: ffff8880606ce170 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb1/0x7c0 drivers/base/dd.c:1302
 #6: ffffffff8dcc7368 (register_mutex#7){+.+.}-{3:3}, at: snd_seq_midisynth_remove+0x68/0x4f0 sound/core/seq/seq_midi.c:459
3 locks held by syz.3.4812/20684:

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7891 Comm: kworker/u4:14 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:__lock_acquire+0x251/0x7c40 kernel/locking/lockdep.c:4973
Code: 30 49 b8 00 00 00 00 00 fc ff df 0f 87 11 65 00 00 48 8b 44 24 20 4c 8d b4 d8 d8 0a 00 00 4c 89 f0 48 c1 e8 03 42 0f b6 04 00 <84> c0 0f 85 7f 65 00 00 48 8b 44 24 58 48 83 7d 10 00 0f 84 00 01
RSP: 0018:ffffc90003dbf580 EFLAGS: 00000806
RAX: 0000000000000000 RBX: 0000000000000019 RCX: ffffffff96c1a103
RDX: 0000000000000029 RSI: 0000000000000000 RDI: ffff8880b8e3ea40
RBP: ffffc90003dbf7b0 R08: dffffc0000000000 R09: 0000000000000001
R10: dffffc0000000000 R11: fffffbfff1c422d6 R12: 0000000000000000
R13: ffff8880b8e3ea40 R14: ffff888025c765a0 R15: 0000000000000029
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8a1a1ef2f8 CR3: 000000007e6aa000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
 put_cpu_partial+0x91/0x250 mm/slub.c:2639
 get_partial_node+0x1b7/0x480 mm/slub.c:2239
 get_partial mm/slub.c:2330 [inline]
 ___slab_alloc+0x96d/0x1240 mm/slub.c:3131
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc_node_track_caller+0xa0/0x240 mm/slab_common.c:956
 kmalloc_reserve net/core/skbuff.c:446 [inline]
 __alloc_skb+0x226/0x7d0 net/core/skbuff.c:515
 alloc_skb include/linux/skbuff.h:1303 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x24f/0xa80 drivers/net/netdevsim/dev.c:851
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>