INFO: task kworker/u4:2:150 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D stack:21280 pid:  150 ppid:     2 flags:0x00004000
Workqueue: events_unbound flush_to_ldisc
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 commit_echoes drivers/tty/n_tty.c:775 [inline]
 n_tty_receive_char+0x5ed/0xbb0 drivers/tty/n_tty.c:1411
 n_tty_receive_buf_standard drivers/tty/n_tty.c:-1 [inline]
 __receive_buf drivers/tty/n_tty.c:1577 [inline]
 n_tty_receive_buf_common+0x170c/0x65b0 drivers/tty/n_tty.c:1674
 tty_port_default_receive_buf+0x69/0x90 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:471 [inline]
 flush_to_ldisc+0x2a1/0x530 drivers/tty/tty_buffer.c:523
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task kworker/0:10:4379 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:10    state:D stack:23408 pid: 4379 ppid:     2 flags:0x00004000
Workqueue: events console_callback
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 __down_common+0x289/0x3b0 kernel/locking/semaphore.c:228
 down+0x7e/0xd0 kernel/locking/semaphore.c:63
 console_lock+0x29/0x70 kernel/printk/printk.c:2557
 console_callback+0x66/0x440 drivers/tty/vt/vt.c:2980
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
6 locks held by kworker/u4:2/150:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000179fd00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888016de00b8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x34/0x530 drivers/tty/tty_buffer.c:495
 #3: ffff8880624f3098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 drivers/tty/tty_ldisc.c:273
 #4: ffff8880624f32e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_receive_buf_common+0x87/0x65b0 drivers/tty/n_tty.c:1637
 #5: ffffc900011fa378 (&ldata->output_lock){+.+.}-{3:3}, at: commit_echoes drivers/tty/n_tty.c:775 [inline]
 #5: ffffc900011fa378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_receive_char+0x5ed/0xbb0 drivers/tty/n_tty.c:1411
4 locks held by udevd/3558:
2 locks held by getty/3946:
 #0: ffff88802cddd098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
4 locks held by kworker/u4:6/4260:
2 locks held by kworker/0:9/4375:
2 locks held by kworker/0:10/4379:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900030afd00 (console_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
2 locks held by udevd/4788:
2 locks held by kworker/u4:8/8433:
5 locks held by syz.2.1637/8500:
2 locks held by syz.2.1637/8502:
2 locks held by syz.4.1971/9484:
 #0: ffff8880624f3098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffff888016de00b8 (&buf->lock){+.+.}-{3:3}, at: tiocsti+0x192/0x270 drivers/tty/tty_io.c:2310
2 locks held by syz.4.1971/9485:
 #0: ffff8880624f3098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffff888016de00b8 (&buf->lock){+.+.}-{3:3}, at: tiocsti+0x192/0x270 drivers/tty/tty_io.c:2310
2 locks held by syz.4.1971/9487:
 #0: ffff8880624f3098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffff888016de00b8 (&buf->lock){+.+.}-{3:3}, at: tiocsti+0x192/0x270 drivers/tty/tty_io.c:2310
1 lock held by syz.1.2023/9654:
 #0: ffff8880624f3098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
2 locks held by syz.6.2250/10219:
2 locks held by sed/11662:
2 locks held by syz.5.2763/11666:

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe1b/0xe60 kernel/hung_task.c:369
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>