INFO: task syz.1.5661:19100 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.5661 state:D stack:26984 pid:19100 tgid:19099 ppid:5812 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5248 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6855
__schedule_loop kernel/sched/core.c:6937 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6952
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7009
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0xcf8/0x1b10 kernel/locking/mutex.c:776
sync_bdevs+0x153/0x480 block/bdev.c:1305
ksys_sync+0xb2/0x150 fs/sync.c:105
__do_sys_sync+0xe/0x20 fs/sync.c:113
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd7f838f749
RSP: 002b:00007fd7f65f6038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd7f85e5fa0 RCX: 00007fd7f838f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd7f85e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd7f85e6038 R14: 00007fd7f85e5fa0 R15: 00007ffc4c3b1058
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e3c95a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e3c95a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e3c95a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:8/2986:
#0: ffff88801fb2a148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3238
#1: ffffc9000c047c90 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3239
2 locks held by getty/5577:
#0: ffff8880323580a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by udevd/5804:
#0: ffff888025bec358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:962
3 locks held by kworker/0:8/5972:
#0: ffff88801bb94d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3238
#1: ffffc9000478fc90 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3239
#2: ffff888145790198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#2: ffff888145790198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x4fe0 drivers/usb/core/hub.c:5898
6 locks held by kworker/1:10/11758:
#0: ffff88801bb94d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3238
#1: ffffc9001e35fc90 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3239
#2: ffff888145718198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline]
#2: ffff888145718198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x4fe0 drivers/usb/core/hub.c:5898
#3: ffffc90000a08ca8 ((&q->adapt_timer)){+.-.}-{0:0}, at: call_timer_fn+0x117/0x5a0 kernel/time/timer.c:1745
#4: ffffffff8e3c95a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#4: ffffffff8e3c95a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#4: ffffffff8e3c95a0 (rcu_read_lock){....}-{1:3}, at: fq_pie_timer+0x54/0x5b0 net/sched/sch_fq_pie.c:395
#5: ffff88803112f908 (&sch->root_lock_key#70){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#5: ffff88803112f908 (&sch->root_lock_key#70){+.-.}-{3:3}, at: fq_pie_timer+0xfd/0x5b0 net/sched/sch_fq_pie.c:397
1 lock held by syz.1.5661/19100:
#0: ffff888025bec358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x153/0x480 block/bdev.c:1305
1 lock held by syz.8.7836/24055:
#0: ffffffff8e3d4a80 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6e0 kernel/rcu/tree.c:3816
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
__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]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf14/0x1140 kernel/hung_task.c:495
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 11758 Comm: kworker/1:10 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: usb_hub_wq hub_event
RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:401
Code: 16 94 fc 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 1a 66 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c c3 cc cc cc cc e8 b8 aa fc fc eb a2 e8 41 ab
RSP: 0018:ffffc9001e35e828 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8529c8c0 RDI: ffffffff9ae44ac0
RBP: ffffffff9ae44a80 R08: 0000000000000001 R09: 000000000000001f
R10: 0000000000000000 R11: 0000000003b77837 R12: 0000000000000000
R13: 0000000000000020 R14: fffffbfff35c89aa R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888124a9c000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f45a25b7198 CR3: 0000000073df1000 CR4: 00000000003526f0
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:137 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:159 [inline]
wait_for_lsr+0x13a/0x210 drivers/tty/serial/8250/8250_port.c:1961
fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3234 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3257 [inline]
serial8250_console_write+0xf81/0x1890 drivers/tty/serial/8250/8250_port.c:3342
console_emit_next_record kernel/printk/printk.c:3111 [inline]
console_flush_all+0x801/0xc60 kernel/printk/printk.c:3199
__console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
console_unlock+0xd8/0x210 kernel/printk/printk.c:3298
vprintk_emit+0x3d7/0x680 kernel/printk/printk.c:2423
dev_vprintk_emit drivers/base/core.c:4914 [inline]
dev_printk_emit+0xfa/0x140 drivers/base/core.c:4925
__dev_printk+0xf5/0x270 drivers/base/core.c:4937
_dev_info+0xe4/0x120 drivers/base/core.c:4983
usb_stor_probe1+0x3c/0x1c10 drivers/usb/storage/usb.c:1028
storage_probe+0x755/0xda0 drivers/usb/storage/usb.c:1233
usb_probe_interface+0x303/0xa40 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:581 [inline]
really_probe+0x241/0xa90 drivers/base/dd.c:659
__driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
__device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
__device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
device_add+0x1148/0x1950 drivers/base/core.c:3689
usb_set_configuration+0x1187/0x1e20 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0xb1/0x110 drivers/usb/core/generic.c:250
usb_probe_device+0xef/0x3e0 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:581 [inline]
really_probe+0x241/0xa90 drivers/base/dd.c:659
__driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
__device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
__device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
device_add+0x1148/0x1950 drivers/base/core.c:3689
usb_new_device+0xd07/0x1a60 drivers/usb/core/hub.c:2694
hub_port_connect drivers/usb/core/hub.c:5566 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
port_event drivers/usb/core/hub.c:5870 [inline]
hub_event+0x2f34/0x4fe0 drivers/usb/core/hub.c:5952
process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3263
process_scheduled_works kernel/workqueue.c:3346 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
vkms_vblank_simulate: vblank timer overrun