INFO: task syz.6.382:6517 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.382       state:D stack:27728 pid:6517  ppid:5501   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2144
 ___down_common kernel/locking/semaphore.c:229 [inline]
 __down_common+0x30c/0x740 kernel/locking/semaphore.c:250
 down+0x7c/0xd0 kernel/locking/semaphore.c:64
 console_lock+0x141/0x1c0 kernel/printk/printk.c:2629
 con_install+0x94/0x720 drivers/tty/vt/vt.c:3381
 tty_driver_install_tty drivers/tty/tty_io.c:1303 [inline]
 tty_init_dev+0xcf/0x4c0 drivers/tty/tty_io.c:1415
 tty_open_by_driver drivers/tty/tty_io.c:2081 [inline]
 tty_open+0x7d3/0xcb0 drivers/tty/tty_io.c:2128
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7dd/0x10b0 fs/open.c:882
 do_open fs/namei.c:3677 [inline]
 path_openat+0x2674/0x2f10 fs/namei.c:3834
 do_filp_open+0x1ee/0x420 fs/namei.c:3861
 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1f7d55fd8e
RSP: 002b:00007f1f7e55cb28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f1f7e55d6c0 RCX: 00007f1f7d55fd8e
RDX: 0000000000000002 RSI: 00007f1f7e55cc00 RDI: ffffffffffffff9c
RBP: 00007f1f7d636b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1f7d826038 R14: 00007f1f7d825fa0 R15: 00007ffe0745b008
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/7:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8db2e230 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8db2ea50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
3 locks held by kworker/0:1/14:
 #0: ffff88814d3a9138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90000137d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8ed760e8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1500 net/ipv6/addrconf.c:4146
1 lock held by khungtaskd/28:
 #0: ffffffff8db2d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8db2d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8db2d8a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6669
2 locks held by kworker/u4:5/648:
 #0: ffff888018479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc900020efd00 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
2 locks held by getty/4026:
 #0: ffff888030d1b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
3 locks held by syz-executor/4284:
3 locks held by kworker/u4:9/4410:
6 locks held by kworker/u4:13/4578:
 #0: ffff888018479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004e1fd00 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff8880186300b8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x34/0x800 drivers/tty/tty_buffer.c:537
 #3: ffff888044316098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 drivers/tty/tty_ldisc.c:264
 #4: ffff8880443162e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_receive_buf_common+0x79/0x1470 drivers/tty/n_tty.c:1684
 #5: ffffc90004119380 (&ldata->output_lock){+.+.}-{3:3}, at: flush_echoes drivers/tty/n_tty.c:815 [inline]
 #5: ffffc90004119380 (&ldata->output_lock){+.+.}-{3:3}, at: __receive_buf drivers/tty/n_tty.c:1625 [inline]
 #5: ffffc90004119380 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_receive_buf_common+0xd51/0x1470 drivers/tty/n_tty.c:1721
2 locks held by kworker/0:2H/5063:
4 locks held by kworker/u4:19/5285:
3 locks held by kworker/u4:20/6003:
1 lock held by syz.8.355/6388:
2 locks held by syz.6.382/6517:
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
 #1: ffff8880599cb1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x70/0x4c0 drivers/tty/tty_io.c:1414
4 locks held by syz-executor/6523:
1 lock held by syz.4.450/6927:
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
2 locks held by kworker/0:17/6982:
 #0: ffff888018470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90003957d00 (console_work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
1 lock held by syz.0.507/7255:
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.1.524/7327:
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8e291168 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by udevd/7404:
2 locks held by syz-executor/7435:
1 lock held by modprobe/7459:

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>