INFO: task syz.0.859:8502 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.859 state:D stack:27968 pid:8502 tgid:8501 ppid:5828 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5352 [inline]
__schedule+0x1665/0x5590 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7047 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7062
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7119
rwsem_down_write_slowpath+0x883/0x1080 kernel/locking/rwsem.c:1215
__down_write_common kernel/locking/rwsem.c:1347 [inline]
__down_write kernel/locking/rwsem.c:1356 [inline]
down_write+0x1bc/0x200 kernel/locking/rwsem.c:1626
mmap_write_lock include/linux/mmap_lock.h:536 [inline]
userfaultfd_register fs/userfaultfd.c:1317 [inline]
userfaultfd_ioctl+0x21fb/0x4c70 fs/userfaultfd.c:2050
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3b9899c799
RSP: 002b:00007f3b9980f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3b98c15fa0 RCX: 00007f3b9899c799
RDX: 0000200000000080 RSI: 00000000c020aa00 RDI: 0000000000000006
RBP: 00007f3b98a32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3b98c16038 R14: 00007f3b98c15fa0 R15: 00007ffdab174088
Showing all locks held in the system:
1 lock held by khungtaskd/30:
#0: ffffffff8eb5d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8eb5d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8eb5d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5589:
#0: ffff88803377e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
6 locks held by kworker/1:4/5872:
#0: ffff8880222fb940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x894/0x1780 kernel/workqueue.c:3261
#1: ffffc900047f7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8bb/0x1780 kernel/workqueue.c:3262
#2: ffff88802b2c3190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:941 [inline]
#2: ffff88802b2c3190 (&dev->mutex){....}-{4:4}, at: hub_event+0x17f/0x4f30 drivers/usb/core/hub.c:5899
#3: ffff88807beaf190 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:941 [inline]
#3: ffff88807beaf190 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1008
#4:
ffff88802b3c7158
(
&dev->mutex
){....}-{4:4}
, at: device_lock include/linux/device.h:941 [inline]
, at: __device_attach+0x88/0x450 drivers/base/dd.c:1008
#5:
ffff8880607500c8
(
&d->usb_mutex
#2
){+.+.}-{4:4}
, at: console_trylock_spinning kernel/printk/printk.c:2026 [inline]
, at: vprintk_emit+0x2cf/0x560 kernel/printk/printk.c:2478
8 locks held by kworker/1:8/5952:
4 locks held by udevd/6002:
1 lock held by syz.0.859/8502:
#0: ffff888033c93538 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:536 [inline]
#0: ffff888033c93538 (&mm->mmap_lock){++++}-{4:4}, at: userfaultfd_register fs/userfaultfd.c:1317 [inline]
#0: ffff888033c93538 (&mm->mmap_lock){++++}-{4:4}, at: userfaultfd_ioctl+0x21fb/0x4c70 fs/userfaultfd.c:2050
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0x1002/0x1060 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 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: 5952 Comm: kworker/1:8 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:401
Code: e8 8e f2 78 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 7f 56 e2 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc90004dd6c30 EFLAGS: 00000002
RAX: 1ffffffff3549d00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 00000000000fffff RDI: 0000000000100000
RBP: ffffffff9aa4f050 R08: ffff8881412c822f R09: 1ffff11028259045
R10: dffffc0000000000 R11: ffffffff854e0020 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9aa4edc0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124ee0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2eb02ff8 CR3: 0000000079dc0000 CR4: 00000000003526f0
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:128 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
wait_for_lsr+0x1a1/0x2f0 drivers/tty/serial/8250/8250_port.c:1970
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3207 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3272 [inline]
serial8250_console_write+0x1348/0x1ba0 drivers/tty/serial/8250/8250_port.c:3357
console_emit_next_record kernel/printk/printk.c:3183 [inline]
console_flush_one_record kernel/printk/printk.c:3269 [inline]
console_flush_all+0x718/0xb20 kernel/printk/printk.c:3343
__console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
dev_vprintk_emit+0x355/0x420 drivers/base/core.c:4913
dev_printk_emit+0xee/0x140 drivers/base/core.c:4924
_dev_notice+0x11e/0x180 drivers/base/core.c:4981
usb_parse_endpoint drivers/usb/core/config.c:427 [inline]
usb_parse_interface drivers/usb/core/config.c:636 [inline]
usb_parse_configuration drivers/usb/core/config.c:849 [inline]
usb_get_configuration+0x2a39/0x54f0 drivers/usb/core/config.c:1002
usb_enumerate_device drivers/usb/core/hub.c:2527 [inline]
usb_new_device+0x145/0x16f0 drivers/usb/core/hub.c:2665
hub_port_connect drivers/usb/core/hub.c:5567 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x2a1c/0x4f30 drivers/usb/core/hub.c:5953
process_one_work+0x9ab/0x1780 kernel/workqueue.c:3289
process_scheduled_works kernel/workqueue.c:3380 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3461
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245