INFO: task syz.2.1562:5635 blocked for more than 122 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1562 state:D stack:0 pid:5635 tgid:5629 ppid:294 flags:0x00000004
Call Trace:
context_switch kernel/sched/core.c:6052 [inline]
__schedule+0x1496/0x20b0 kernel/sched/core.c:7865
__schedule_loop kernel/sched/core.c:7942 [inline]
schedule+0xc5/0x240 kernel/sched/core.c:7957
schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8014
__mutex_lock_common kernel/locking/mutex.c:707 [inline]
__mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806
__mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
device_lock include/linux/device.h:911 [inline]
usbdev_open+0x156/0x840 drivers/usb/core/devio.c:1051
chrdev_open+0x4eb/0x610 fs/char_dev.c:414
do_dentry_open+0x97c/0x1510 fs/open.c:960
vfs_open+0x86/0x240 fs/open.c:1092
do_open fs/namei.c:3782 [inline]
path_openat+0x2c49/0x35a0 fs/namei.c:3941
do_filp_open+0x1f2/0x440 fs/namei.c:3968
do_sys_openat2+0x134/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_openat fs/open.c:1471 [inline]
__se_sys_openat fs/open.c:1466 [inline]
__x64_sys_openat+0x13a/0x170 fs/open.c:1466
x64_sys_call+0xe69/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f301215d68e
RSP: 002b:00007f3012fedb28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f3012fee6c0 RCX: 00007f301215d68e
RDX: 0000000000044680 RSI: 00007f3012fedc00 RDI: ffffffffffffff9c
RBP: 00007f3012fedc00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f3012416128 R14: 00007f3012416090 R15: 00007ffef15752c8
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 e549a79720f8b9d2445064a5e8a439d230f1aa2c
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
__dump_stack+0x21/0x30 lib/dump_stack.c:94
dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
dump_stack+0x19/0x20 lib/dump_stack.c:129
nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
watchdog+0xe45/0xf90 kernel/hung_task.c:423
kthread+0x2c7/0x360 kernel/kthread.c:389
ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 66 Comm: kworker/0:2 Not tainted syzkaller #0 e549a79720f8b9d2445064a5e8a439d230f1aa2c
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:io_serial_out+0x85/0xd0 drivers/tty/serial/8250/8250_port.c:413
Code: fe 44 89 e1 41 d3 e6 49 83 c7 08 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 54 46 bd fe 45 03 37 89 d8 44 89 f2 ee <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 e1 80 e1 07
RSP: 0018:ffffc90000d6efc8 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000043d31 RDI: 0000000000043d32
RBP: ffffc90000d6eff0 R08: ffff888105afc107 R09: 1ffff11020b5f820
R10: 0000000000000000 R11: ffffffff8322dc60 R12: 0000000000000000
R13: dffffc0000000000 R14: 00000000000003f8 R15: ffffffff88c38488
FS: 0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc695b41000 CR3: 0000000121e2e000 CR4: 00000000003526b0
Call Trace:
serial_out drivers/tty/serial/8250/8250.h:142 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:-1 [inline]
serial8250_console_write+0x16a6/0x2150 drivers/tty/serial/8250/8250_port.c:3427
univ8250_console_write+0x71/0xb0 drivers/tty/serial/8250/8250_core.c:396
console_emit_next_record kernel/printk/printk.c:3151 [inline]
console_flush_all+0x5e6/0xab0 kernel/printk/printk.c:3239
__console_flush_and_unlock kernel/printk/printk.c:3298 [inline]
console_unlock+0xf8/0x2c0 kernel/printk/printk.c:3338
vprintk_emit+0x282/0x650 kernel/printk/printk.c:2462
dev_vprintk_emit+0x33c/0x400 drivers/base/core.c:4962
dev_printk_emit+0xef/0x150 drivers/base/core.c:4973
__dev_printk+0x17f/0x1b0 drivers/base/core.c:4985
_dev_info+0x11f/0x180 drivers/base/core.c:5031
show_string drivers/usb/core/hub.c:2409 [inline]
announce_device+0x1c9/0x2c0 drivers/usb/core/hub.c:2426
usb_new_device+0x4a1/0x1500 drivers/usb/core/hub.c:2684
hub_port_connect drivers/usb/core/hub.c:5574 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5714 [inline]
port_event drivers/usb/core/hub.c:5878 [inline]
hub_event+0x2dbd/0x4360 drivers/usb/core/hub.c:5960
process_one_work kernel/workqueue.c:3273 [inline]
process_scheduled_works+0x7f7/0x1060 kernel/workqueue.c:3354
worker_thread+0xc99/0x13f0 kernel/workqueue.c:3435
kthread+0x2c7/0x360 kernel/kthread.c:389
ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244