INFO: task kworker/0:1:11 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1 state:D stack:20632 pid:11 tgid:11 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x1325/0x47e0 kernel/sched/core.c:7276
__schedule_loop kernel/sched/core.c:7353 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7368
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7425
rwsem_down_write_slowpath+0x4c2/0x12a0 kernel/locking/rwsem.c:1215
__down_write_common kernel/locking/rwsem.c:1347 [inline]
__down_write kernel/locking/rwsem.c:1356 [inline]
down_write+0x1c0/0x1f0 kernel/locking/rwsem.c:1632
usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
usbtmc_probe+0xff8/0x1bc0 drivers/usb/class/usbtmc.c:2488
usb_probe_interface+0x386/0x9b0 drivers/usb/core/driver.c:399
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x210/0x460 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:3776
usb_set_configuration+0xd97/0x1c60 drivers/usb/core/message.c:2268
usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:293
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x210/0x460 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:3776
usb_new_device.part.0+0xcc2/0x1686 drivers/usb/core/hub.c:2708
usb_new_device drivers/usb/core/hub.c:5833 [inline]
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.cold+0x51a/0xe9d drivers/usb/core/hub.c:5966
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
INFO: task kworker/1:4:5245 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:4 state:D stack:19688 pid:5245 tgid:5245 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x1325/0x47e0 kernel/sched/core.c:7276
__schedule_loop kernel/sched/core.c:7353 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7368
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7425
rwsem_down_write_slowpath+0x4c2/0x12a0 kernel/locking/rwsem.c:1215
__down_write_common kernel/locking/rwsem.c:1347 [inline]
__down_write kernel/locking/rwsem.c:1356 [inline]
down_write+0x1c0/0x1f0 kernel/locking/rwsem.c:1632
usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
usblp_probe+0x1194/0x14f0 drivers/usb/class/usblp.c:1220
usb_probe_interface+0x386/0x9b0 drivers/usb/core/driver.c:399
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x210/0x460 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:3776
usb_set_configuration+0xd97/0x1c60 drivers/usb/core/message.c:2268
usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:293
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x210/0x460 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:3776
usb_new_device.part.0+0xcc2/0x1686 drivers/usb/core/hub.c:2708
usb_new_device drivers/usb/core/hub.c:5833 [inline]
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.cold+0x51a/0xe9d drivers/usb/core/hub.c:5966
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
INFO: task kworker/1:7:5975 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:7 state:D stack:21560 pid:5975 tgid:5975 ppid:2 task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x1325/0x47e0 kernel/sched/core.c:7276
__schedule_loop kernel/sched/core.c:7353 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7368
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7425
rwsem_down_write_slowpath+0x4c2/0x12a0 kernel/locking/rwsem.c:1215
__down_write_common kernel/locking/rwsem.c:1347 [inline]
__down_write kernel/locking/rwsem.c:1356 [inline]
down_write+0x1c0/0x1f0 kernel/locking/rwsem.c:1632
usb_deregister_dev+0x7c/0x210 drivers/usb/core/file.c:186
sisusb_disconnect+0x5e/0x200 drivers/usb/misc/sisusbvga/sisusbvga.c:2921
usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:618 [inline]
device_remove+0x12a/0x180 drivers/base/dd.c:610
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
device_del+0x376/0x9b0 drivers/base/core.c:3965
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
usb_disconnect+0x2e2/0x9a0 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+0x1d46/0x4510 drivers/usb/core/hub.c:5966
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
INFO: task kworker/1:8:5976 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:21224 pid:5976 tgid:5976 ppid:2 task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x1325/0x47e0 kernel/sched/core.c:7276
__schedule_loop kernel/sched/core.c:7353 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7368
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7425
rwsem_down_write_slowpath+0x4c2/0x12a0 kernel/locking/rwsem.c:1215
__down_write_common kernel/locking/rwsem.c:1347 [inline]
__down_write kernel/locking/rwsem.c:1356 [inline]
down_write+0x1c0/0x1f0 kernel/locking/rwsem.c:1632
usb_deregister_dev+0x7c/0x210 drivers/usb/core/file.c:186
usbtmc_disconnect+0x4c/0x400 drivers/usb/class/usbtmc.c:2511
usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:461
device_remove drivers/base/dd.c:618 [inline]
device_remove+0x12a/0x180 drivers/base/dd.c:610
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
device_del+0x376/0x9b0 drivers/base/core.c:3965
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
usb_disconnect+0x2e2/0x9a0 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+0x1d46/0x4510 drivers/usb/core/hub.c:5966
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x69f/0xc90 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/0:1/11: 6, on CPU#0:
#0: ffff8881042e4140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc900000bfd18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff888109f271d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff888109f271d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4510 drivers/usb/core/hub.c:5912
#3: ffff888107f251d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff888107f251d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#4: ffff8881195c61a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff8881195c61a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#5: ffffffff8a555028
(minor_rwsem){++++}-{4:4}, at: usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
locks held by pr/ttyS0/15: 1, last CPU#1:
#0: ffffffff898d0ef8 (
console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x49/0x60 kernel/printk/printk.c:291
locks held by kworker/1:0/24: 6, on CPU#1:
#0: ffff8881042e4140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc9000019fd18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff88810a38f1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88810a38f1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4510 drivers/usb/core/hub.c:5912
#3: ffff8881189001d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff8881189001d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#4: ffff8881189041a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff8881189041a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#5: ffffffff8a555028 (minor_rwsem){++++}-{4:4}, at: usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
locks held by khungtaskd/31: 1, last CPU#0:
#0: ffffffff898e4c20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff898e4c20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff898e4c20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6871
locks held by getty/2933: 2, on CPU#1:
#0: ffff8881012d90a0 (&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
locks held by kworker/1:4/5245: 6, on CPU#1:
#0: ffff8881042e4140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc900023ffd18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff888109fe71d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff888109fe71d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4510 drivers/usb/core/hub.c:5912
#3: ffff888136ebc1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff888136ebc1d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#4: ffff888104a901a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff888104a901a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1073
#5: ffffffff8a555028 (minor_rwsem){++++}-{4:4}, at: usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
locks held by udevd/5279: 4, on CPU#1:
#0: ffff888123185cf8 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183
#1: ffff8881230a8480 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165
#2: ffff888136c8d788 (kn->active#10){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#2: ffff888136c8d788 (kn->active#10){.+.+}-{0:0}, at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:166
#3: ffff888136ebc1d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline]
#3: ffff888136ebc1d8 (&dev->mutex){....}-{4:4}, at: product_show+0x26/0xa0 drivers/usb/core/sysfs.c:141
locks held by kworker/1:7/5975: 6, on CPU#1:
#0: ffff8881042e4140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90014f8fd18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff8881097471d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff8881097471d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4510 drivers/usb/core/hub.c:5912
#3: ffff88811e92d1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff88811e92d1d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x10a/0x9a0 drivers/usb/core/hub.c:2341
#4: ffff88811df3d1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff88811df3d1a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
#4: ffff88811df3d1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1369
#5: ffffffff8a555028 (minor_rwsem){++++}-{4:4}, at: usb_deregister_dev+0x7c/0x210 drivers/usb/core/file.c:186
locks held by kworker/1:8/5976: 6, on CPU#1:
#0: ffff8881042e4140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90014fe7d18 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff888109bd71d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff888109bd71d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4510 drivers/usb/core/hub.c:5912
#3: ffff88811d95a1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff88811d95a1d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x10a/0x9a0 drivers/usb/core/hub.c:2341
#4: ffff88811ddcc1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff88811ddcc1a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
#4: ffff88811ddcc1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1369
#5: ffffffff8a555028 (minor_rwsem){++++}-{4:4}, at: usb_deregister_dev+0x7c/0x210 drivers/usb/core/file.c:186
locks held by syz.0.442/6736: 2, on CPU#1:
#0: ffffffff8a555028 (minor_rwsem){++++}-{4:4}, at: usb_open+0x23/0x220 drivers/usb/core/file.c:38
#1: ffff88811c3b68c8 (&(sisusb->lock)){+.+.}-{4:4}, at: sisusb_open+0xb6/0x4b0 drivers/usb/misc/sisusbvga/sisusbvga.c:2213
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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:123
nmi_trigger_cpumask_backtrace+0x21f/0x2a0 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+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+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 15 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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 c3 cc cc cc cc e8 31 2d ee fe eb a0 e8 ba 2d ee
RSP: 0018:ffffc900000ff9f0 EFLAGS: 00000002
RAX: 0000000000000068 RBX: 00000000000003f8 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: ffffffff8331bbc5 RDI: ffffffff9448c820
RBP: ffffffff9448c7e0 R08: 0000000000000001 R09: 000000000000001f
R10: 0000000000000000 R11: 205d313354202020 R12: 0000000000000000
R13: 0000000000000068 R14: 000000000000000f R15: ffffc900000ffdb8
FS: 0000000000000000(0000) GS:ffff8882684e2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4334cf72c0 CR3: 00000001251dc000 CR4: 00000000003506f0
Call Trace:
serial_port_out include/linux/serial_core.h:817 [inline]
serial8250_console_putchar drivers/tty/serial/8250/8250_port.c:3287 [inline]
__serial8250_console_fifo_write+0xd6/0x290 drivers/tty/serial/8250/8250_port.c:3359
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+0xf46/0x1330 drivers/tty/serial/8250/8250_port.c:3493
nbcon_emit_next_record+0x8f7/0xa70 kernel/printk/nbcon.c:1070
nbcon_emit_one+0x1a8/0x2b0 kernel/printk/nbcon.c:1157
nbcon_kthread_func+0x613/0x7d0 kernel/printk/nbcon.c:1271
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x69f/0xc90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245