syzbot

INFO: task kworker/1:1:22268 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1     state:D stack:22840 pid:22268 tgid:22268 ppid:2      task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x145d/0x4a00 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6960
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7017
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0xc69/0x1ca0 kernel/locking/mutex.c:776
 rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 rtnl_net_dev_lock+0x146/0x360 net/core/dev.c:2143
 unregister_netdev+0x15/0x60 net/core/dev.c:12461
 usbnet_disconnect+0x109/0x510 drivers/net/usb/usbnet.c:1676
 usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:458
 device_remove drivers/base/dd.c:571 [inline]
 device_remove+0x125/0x170 drivers/base/dd.c:563
 __device_release_driver drivers/base/dd.c:1282 [inline]
 device_release_driver_internal+0x44b/0x620 drivers/base/dd.c:1305
 bus_remove_device+0x22f/0x450 drivers/base/bus.c:616
 device_del+0x396/0x9f0 drivers/base/core.c:3878
 usb_disable_device+0x355/0x820 drivers/usb/core/message.c:1418
 usb_disconnect+0x2e1/0x9e0 drivers/usb/core/hub.c:2345
 hub_port_connect drivers/usb/core/hub.c:5407 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x1b50/0x5420 drivers/usb/core/hub.c:5953
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x74f/0xa30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff892cd6e0
 (
rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
6 locks held by kworker/0:2/2819:
 #0: ffff8881062a8548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}
, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: 
ffffc9000405fca0 (
(work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: 
ffff88810a3c4198
 (&dev->mutex){....}-{4:4}
, at: device_lock include/linux/device.h:895 [inline]
, at: hub_event+0x1be/0x5420 drivers/usb/core/hub.c:5899
 #3: ffff88811db7f198
 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
 #4: ffff88811cdb7160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff88811cdb7160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
 #5: 
ffffffff8a666c68 (rtnl_mutex){+.+.}-{4:4}
, at: ieee80211_register_hw+0x21b5/0x41d0 net/mac80211/main.c:1533
1 lock held by dhcpcd/2898:
2 locks held by getty/2921:
 #0: ffff888115c810a0
 (&tty->ldisc_sem){++++}-{0:0}
, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900000452f0
 (&ldata->atomic_read_lock
){+.+.}-{4:4}, at: n_tty_read+0x41b/0x1510 drivers/tty/n_tty.c:2211
6 locks held by kworker/1:4/5229:
 #0: ffff8881062a8548
 (
(wq_completion)usb_hub_wq
){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc900022bfca0 (
(work_completion)(&hub->events)){+.+.}-{0:0}
, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff88810a7b0198 (&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:895 [inline]
, at: hub_event+0x1be/0x5420 drivers/usb/core/hub.c:5899
 #3: ffff8881132dc198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #3: ffff8881132dc198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
 #4: ffff888136219160 (&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:895 [inline]
, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
 #5: 
ffffffff8a666c68 (rtnl_mutex){+.+.}-{4:4}
, at: wiphy_apply_custom_regulatory+0x23d/0x3c0 net/wireless/reg.c:2624
5 locks held by kworker/0:4/5305:
3 locks held by kworker/1:6/5361:
6 locks held by kworker/0:5/15856:
 #0: 
ffff8881062a8548
 (
(wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc9000229fca0
 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff888109fb4198
 (&dev->mutex){....}-{4:4}
, at: device_lock include/linux/device.h:895 [inline]
, at: hub_event+0x1be/0x5420 drivers/usb/core/hub.c:5899
 #3: ffff888135c8a198
 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
 #4: ffff88811edc5160
 (&dev->mutex){....}-{4:4}
, at: device_lock include/linux/device.h:895 [inline]
, at: __device_attach+0x7e/0x4e0 drivers/base/dd.c:1006
 #5: ffffffff8a666c68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock_killable include/linux/rtnetlink.h:145 [inline]
 #5: ffffffff8a666c68 (rtnl_mutex){+.+.}-{4:4}, at: register_netdev+0x18/0x50 net/core/dev.c:11504
4 locks held by udevd/19391:
 #0: ffff88810a799d58 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x12d0 fs/seq_file.c:182
 #1: 
ffff8881213c6c88 (&of->mutex){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
 #2: ffff888115744878 (
kn->active#14
){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
){++++}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
 #3: ffff8881132dc198 (&dev->mutex){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:900 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
4 locks held by udevd/19405:
 #0: ffff888125fc2790 (&p->lock){+.+.}-{4:4}
, at: seq_read_iter+0xe1/0x12d0 fs/seq_file.c:182
 #1: ffff88811daa5088 (&of->mutex){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
 #2: ffff88811507ed28
 (
kn->active#14
){++++}-{0:0}
, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
 #3: ffff88811db7f198 (
&dev->mutex){....}-{4:4}
, at: device_lock_interruptible include/linux/device.h:900 [inline]
, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
4 locks held by udevd/19433:
 #0: ffff8881146d3418
 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x12d0 fs/seq_file.c:182
 #1: 
ffff88811d0bf488 (
&of->mutex){+.+.}-{4:4}
, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172
 #2: ffff88814b2d81e8
 (kn->active#14){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 (kn->active#14){++++}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:173
 #3: 
ffff888135c8a198
 (&dev->mutex
){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:900 [inline]
){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
3 locks held by kworker/1:7/19946:
 #0: ffff888100072948
 ((wq_completion)events_power_efficient
){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc900031bfca0
 ((reg_check_chans).work
){+.+.}-{0:0}
, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffffffff8a666c68
 (rtnl_mutex
){+.+.}-{4:4}, at: reg_check_chans_work+0x91/0x1190 net/wireless/reg.c:2453
3 locks held by kworker/u8:5/21172:
 #0: ffff8881103f1948
 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}
, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc90003ccfca0
 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)
){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffffffff8a666c68 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8a666c68 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4734
6 locks held by kworker/1:1/22268:
 #0: ffff8881062a8548
 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc900015c7ca0 ((work_completion)(&hub->events)
){+.+.}-{0:0}
, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff88810a3dc198
 (
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:895 [inline]
, at: hub_event+0x1be/0x5420 drivers/usb/core/hub.c:5899
 #3: ffff888117656198 (
&dev->mutex
){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
){....}-{4:4}, at: usb_disconnect+0x10a/0x9e0 drivers/usb/core/hub.c:2336
 #4: ffff8881158c8160
 (
&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1104 [inline]
&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xa4/0x620 drivers/base/dd.c:1302
 #5: 
ffffffff8a666c68 (
rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x146/0x360 net/core/dev.c:2143

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:160 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x133/0x180 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xe66/0x1180 kernel/hung_task.c:515
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x74f/0xa30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 12555 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events legacy_dvb_usb_read_remote_control
RIP: 0010:number+0x1ca/0xc70 lib/vsprintf.c:476
Code: 84 c1 0f 85 80 0a 00 00 8b 44 24 7c 48 8d 7c 24 7a 48 ba 00 00 00 00 00 fc ff df 89 44 24 14 48 89 f8 48 c1 e8 03 0f b6 0c 10 <48> 8d 44 24 7b 48 89 c6 48 c1 ee 03 0f b6 14 16 48 89 fe 83 e6 07
RSP: 0018:ffffc90012f47140 EFLAGS: 00000a02
RAX: 1ffff920025e8e37 RBX: ffffc90012f47541 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffc90012f471ba
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 00000000009a5480 R12: 0000000000000801
R13: 0000000000000a0c R14: ffffc90092f4753f R15: 000000000000000a
FS:  0000000000000000(0000) GS:ffff888268cf4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffea9efca8 CR3: 00000001196c0000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 vsnprintf+0x5fa/0x11e0 lib/vsprintf.c:2911
 sprintf+0xcc/0x100 lib/vsprintf.c:3110
 print_time kernel/printk/printk.c:1357 [inline]
 info_print_prefix+0x25a/0x350 kernel/printk/printk.c:1383
 record_print_text+0x140/0x400 kernel/printk/printk.c:1432
 printk_get_next_message+0x2d1/0x6d0 kernel/printk/printk.c:3018
 console_emit_next_record kernel/printk/printk.c:3083 [inline]
 console_flush_one_record+0x684/0xc60 kernel/printk/printk.c:3215
 console_flush_all kernel/printk/printk.c:3289 [inline]
 __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
 console_unlock+0xef/0x240 kernel/printk/printk.c:3359
 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2426
 _printk+0xc7/0x100 kernel/printk/printk.c:2451
 m920x_read drivers/media/usb/dvb-usb/m920x.c:40 [inline]
 m920x_rc_query+0x496/0x770 drivers/media/usb/dvb-usb/m920x.c:193
 legacy_dvb_usb_read_remote_control+0x10c/0x4f0 drivers/media/usb/dvb-usb/dvb-usb-remote.c:123
 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x74f/0xa30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>