syzbot

INFO: task kworker/0:0:9 blocked for more than 143 seconds.
      Not tainted 6.16.0-rc7-syzkaller-g51d4b0a44c82 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:0     state:D
 stack:23112 pid:9     tgid:9     ppid:2      task_flags:0x4288060 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x1325/0x3b10 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6879
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6936
 rwsem_down_write_slowpath+0x524/0x1310 kernel/locking/rwsem.c:1176
 __down_write_common kernel/locking/rwsem.c:1304 [inline]
 __down_write kernel/locking/rwsem.c:1313 [inline]
 down_write+0x1d6/0x200 kernel/locking/rwsem.c:1578
 kernfs_remove_by_name_ns+0x3d/0x110 fs/kernfs/dir.c:1712
 kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
 sysfs_unmerge_group+0xe7/0x170 fs/sysfs/group.c:402
 dev_pm_qos_constraints_destroy+0x30/0x780 drivers/base/power/qos.c:260
 dpm_sysfs_remove+0x70/0xb0 drivers/base/power/sysfs.c:831
 device_del+0x1a0/0x9f0 drivers/base/core.c:3856
 device_unregister+0x1d/0xc0 drivers/base/core.c:3922
 usb_remove_ep_devs+0x42/0x80 drivers/usb/core/endpoint.c:189
 remove_intf_ep_devs drivers/usb/core/message.c:1266 [inline]
 usb_disable_device+0x309/0x7d0 drivers/usb/core/message.c:1417
 usb_disconnect+0x2e1/0x9c0 drivers/usb/core/hub.c:2344
 hub_port_connect drivers/usb/core/hub.c:5406 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x1aa2/0x5060 drivers/usb/core/hub.c:5952
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x5b3/0x6c0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task jbd2/sda1-8:2804 blocked for more than 143 seconds.
      Not tainted 6.16.0-rc7-syzkaller-g51d4b0a44c82 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:jbd2/sda1-8     state:D
 stack:26392 pid:2804  tgid:2804  ppid:2      task_flags:0x240040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x1325/0x3b10 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6879
 io_schedule+0xbf/0x130 kernel/sched/core.c:7724
 bit_wait_io+0x15/0xe0 kernel/sched/wait_bit.c:247
 __wait_on_bit+0x62/0x180 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0xd9/0x110 kernel/sched/wait_bit.c:64
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 __wait_on_buffer+0x64/0x70 fs/buffer.c:123
 wait_on_buffer include/linux/buffer_head.h:422 [inline]
 journal_wait_on_commit_record fs/jbd2/commit.c:171 [inline]
 jbd2_journal_commit_transaction+0x4a88/0x68f0 fs/jbd2/commit.c:881
 kjournald2+0x1f4/0x760 fs/jbd2/journal.c:201
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x5b3/0x6c0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
6 locks held by kworker/0:0/9:
 #0: ffff8881066f3148
 (
(wq_completion)usb_hub_wq){+.+.}-{0:0}
, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: 
ffffc9000009fd10
 (
(work_completion)(&hub->events)){+.+.}-{0:0}
, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: 
ffff88810b71f198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: hub_event+0x1be/0x5060 drivers/usb/core/hub.c:5898
 #3: 
ffff888116c4d198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: usb_disconnect+0x10a/0x9c0 drivers/usb/core/hub.c:2335
 #4: ffffffff897bdb68
 (
dev_pm_qos_sysfs_mtx
){+.+.}-{4:4}
, at: dev_pm_qos_constraints_destroy+0x28/0x780 drivers/base/power/qos.c:254
 #5: ffff888100ac4988
 (
&root->kernfs_rwsem
){++++}-{4:4}
, at: kernfs_remove_by_name_ns+0x3d/0x110 fs/kernfs/dir.c:1712
5 locks held by ksoftirqd/1/22:
5 locks held by kworker/1:0/23:
 #0: ffff8881066f3148
 (
(wq_completion)usb_hub_wq
){+.+.}-{0:0}
, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc9000018fd10
 (
(work_completion)(&hub->events)){+.+.}-{0:0}
, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: 
ffff88810b737198
 (
&dev->mutex){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: hub_event+0x1be/0x5060 drivers/usb/core/hub.c:5898
 #3: 
ffff88811be67198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1004
 #4: 
ffff888100ac4988
 (
&root->kernfs_rwsem
){++++}-{4:4}
, at: kernfs_activate fs/kernfs/dir.c:1425 [inline]
, at: kernfs_add_one+0x349/0x840 fs/kernfs/dir.c:834
1 lock held by khungtaskd/30:
 #0: 
ffffffff890c8440
 (
rcu_read_lock
){....}-{1:3}
, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6770
5 locks held by kworker/1:1/37:
1 lock held by udevd/2843:
 #0: 
ffff888100ac4988
 (
&root->kernfs_rwsem){++++}-{4:4}
, at: kernfs_dop_revalidate+0xa5/0x740 fs/kernfs/dir.c:1180
2 locks held by getty/2907:
 #0: 
ffff8881123620a0
 (
&tty->ldisc_sem
){++++}-{0:0}
, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: 
ffffc900000432f0
 (
&ldata->atomic_read_lock){+.+.}-{4:4}
, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
8 locks held by kworker/1:2/2937:
 #0: 
ffff8881066f3148
 (
(wq_completion)usb_hub_wq
){+.+.}-{0:0}
, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: 
ffffc90000557d10
 (
(work_completion)(&hub->events)
){+.+.}-{0:0}
, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: 
ffff88810b7cf198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: hub_event+0x1be/0x5060 drivers/usb/core/hub.c:5898
 #3: ffff88811bc35198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1004
 #4: ffff88811c07f160
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:884 [inline]
, at: __device_attach+0x7e/0x4b0 drivers/base/dd.c:1004
 #5: 
ffffffff89c1b1b0
 (minor_rwsem
){+.+.}-{4:4}
, at: usb_register_dev+0x11d/0x560 drivers/usb/core/file.c:134
 #6: 
ffffffff897a7168
 (
gdp_mutex
){+.+.}-{4:4}
, at: get_device_parent+0x10a/0x4e0 drivers/base/core.c:3269
 #7: 
ffff888100ac4988
 (
&root->kernfs_rwsem){++++}-{4:4}
, at: kernfs_add_one+0x38/0x840 fs/kernfs/dir.c:791
4 locks held by udevd/2970:
 #0: 
ffff8881195800a0
 (
&p->lock
){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x12c0 fs/seq_file.c:182
 #1: 
ffff88811b6eb088
 (
&of->mutex
#2
){+.+.}-{4:4}
, at: kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
 #2: 
ffff888112c6a968
 (
kn->active#19
){.+.+}-{0:0}
, at: kernfs_seq_start+0x71/0x240 fs/kernfs/file.c:155
 #3: 
ffff88811bc50198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:889 [inline]
, at: product_show+0x26/0xa0 drivers/usb/core/sysfs.c:141
1 lock held by udevd/2971:
 #0: 
ffff888100ac4988
 (
&root->kernfs_rwsem
){++++}-{4:4}
, at: kernfs_dop_revalidate+0xa5/0x740 fs/kernfs/dir.c:1180
3 locks held by kworker/1:3/2972:
2 locks held by udevd/2974:
 #0: 
ffff8881270c5a28 (
&type->i_mutex_dir_key
#4){++++}-{4:4}
, at: inode_lock_shared include/linux/fs.h:884 [inline]
, at: open_last_lookups fs/namei.c:3815 [inline]
, at: path_openat+0x818/0x2cb0 fs/namei.c:4052
 #1: 
ffff888100ac4988
 (
&root->kernfs_rwsem){++++}-{4:4}
, at: kernfs_iop_lookup+0x5b/0x2d0 fs/kernfs/dir.c:1222
1 lock held by udevd/2978:
 #0: 
ffffffff890d3a38
 (
rcu_state.exp_mutex
){+.+.}-{4:4}, at: exp_funnel_lock+0x284/0x3c0 kernel/rcu/tree_exp.h:304
1 lock held by udevd/3000:
 #0: 
ffff888100ac4988
 (
&root->kernfs_rwsem){++++}-{4:4}
, at: kernfs_dop_revalidate+0xa5/0x740 fs/kernfs/dir.c:1180
1 lock held by udevd/3004:
 #0: 
ffff888100ac4988
 (
&root->kernfs_rwsem
){++++}-{4:4}
, at: kernfs_dop_revalidate+0x397/0x740 fs/kernfs/dir.c:1162
4 locks held by udevd/3005:
 #0: 
ffff88811bd7e8b8
 (
&p->lock
){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x12c0 fs/seq_file.c:182
 #1: 
ffff888119f27888
 (
&of->mutex#2
){+.+.}-{4:4}
, at: kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
 #2: 
ffff888113de7698
 (
kn->active
#18){++++}-{0:0}
, at: kernfs_seq_start+0x71/0x240 fs/kernfs/file.c:155
 #3: 
ffff88811be67198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:889 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
4 locks held by udevd/3007:
 #0: 
ffff88811bd98540
 (
&p->lock){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x12c0 fs/seq_file.c:182
 #1: 
ffff88811bff9888
 (
&of->mutex
#2
){+.+.}-{4:4}
, at: kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
 #2: 
ffff8881138c4d28
 (
kn->active#18
){++++}-{0:0}
, at: kernfs_seq_start+0x71/0x240 fs/kernfs/file.c:155
 #3: 
ffff88811bc35198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:889 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
4 locks held by udevd/3012:
 #0: 
ffff88811bd982f0
 (
&p->lock
){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x12c0 fs/seq_file.c:182
 #1: 
ffff88811bff9088
 (
&of->mutex#2
){+.+.}-{4:4}
, at: kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154
 #2: 
ffff8881138c4d28
 (
kn->active
#18){++++}-{0:0}
, at: kernfs_seq_start+0x71/0x240 fs/kernfs/file.c:155
 #3: 
ffff88811bc35198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:889 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.16.0-rc7-syzkaller-g51d4b0a44c82 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
 watchdog+0xf70/0x12c0 kernel/hung_task.c:470
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x5b3/0x6c0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
imon 3-1:155.0: imon usb_rx_callback_intf0: status(-71): ignored
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 22 Comm: ksoftirqd/1 Not tainted 6.16.0-rc7-syzkaller-g51d4b0a44c82 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:io_serial_out+0x8f/0xb0 drivers/tty/serial/8250/8250_port.c:416
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 46 87 5c 04 e8 c1 1e 05 ff eb a0 e8 4a 1f 05
RSP: 0018:ffffc9000017f320 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: ffffffff82d57865 RDI: ffffffff9392af80
RBP: ffffffff9392af40 R08: 0000000000000001 R09: 000000000000001f
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff9392af40 R15: ffffffff9392b200
FS:  0000000000000000(0000) GS:ffff888269260000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005609fa9bf000 CR3: 0000000128c04000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 serial_out drivers/tty/serial/8250/8250.h:142 [inline]
 serial8250_clear_IER+0x9b/0xc0 drivers/tty/serial/8250/8250_port.c:713
 serial8250_console_write+0x255/0x1890 drivers/tty/serial/8250/8250_port.c:3421
 console_emit_next_record kernel/printk/printk.c:3138 [inline]
 console_flush_all+0x801/0xc60 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
 vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
 dev_vprintk_emit drivers/base/core.c:4917 [inline]
 dev_printk_emit+0xfa/0x140 drivers/base/core.c:4928
 __dev_printk+0xf5/0x270 drivers/base/core.c:4940
 _dev_warn+0xe4/0x120 drivers/base/core.c:4984
 usb_rx_callback_intf0+0x11c/0x1a0 drivers/media/rc/imon.c:1768
 __usb_hcd_giveback_urb+0x38d/0x6e0 drivers/usb/core/hcd.c:1663
 usb_hcd_giveback_urb+0x39b/0x450 drivers/usb/core/hcd.c:1747
 dummy_timer+0x1814/0x3a30 drivers/usb/gadget/udc/dummy_hcd.c:1995
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x1ff/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1842
 handle_softirqs+0x208/0x8d0 kernel/softirq.c:579
 run_ksoftirqd kernel/softirq.c:968 [inline]
 run_ksoftirqd+0x3a/0x60 kernel/softirq.c:960
 smpboot_thread_fn+0x3f4/0xae0 kernel/smpboot.c:164
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x5b3/0x6c0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.159 msecs