INFO: task syz.3.426:6826 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.426       state:D stack:26864 pid: 6826 ppid:  6169 flags:0x00004004
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
 do_con_write+0xfb/0x6c40 drivers/tty/vt/vt.c:2908
 con_write+0x1f/0x40 drivers/tty/vt/vt.c:3295
 process_output_block drivers/tty/n_tty.c:592 [inline]
 n_tty_write+0xd19/0x1220 drivers/tty/n_tty.c:2339
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x50c/0x8a0 drivers/tty/tty_io.c:1110
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4328426159
RSP: 002b:00007f432665d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f43286ae090 RCX: 00007f4328426159
RDX: 0000000000001006 RSI: 0000200000001980 RDI: 000000000000000a
RBP: 00007f43284bd06b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f43286ae128 R14: 00007f43286ae090 R15: 00007fff7658c6e8
 </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
2 locks held by kworker/u4:1/144:
2 locks held by kworker/0:1H/1092:
2 locks held by getty/3940:
 #0: ffff88814d00f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900021ce2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
3 locks held by kworker/0:5/4276:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900031cfd00 (key_gc_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #2: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
5 locks held by kworker/u4:10/4378:
3 locks held by kworker/0:9/4830:
 #0: ffff88814c850538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000150fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1530 net/ipv6/addrconf.c:4120
2 locks held by kworker/0:10/4831:
1 lock held by syz.7.286/5953:
1 lock held by syz-executor/6586:
4 locks held by syz.3.426/6826:
 #0: ffff88807d19a098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffff88807d19a130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:961 [inline]
 #1: ffff88807d19a130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:984 [inline]
 #1: ffff88807d19a130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: file_tty_write+0x23c/0x8a0 drivers/tty/tty_io.c:1110
 #2: ffff88807d19a2e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x1ec/0x1220 drivers/tty/n_tty.c:2322
 #3: ffffc90001558378 (&ldata->output_lock){+.+.}-{3:3}, at: process_output_block drivers/tty/n_tty.c:547 [inline]
 #3: ffffc90001558378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x66a/0x1220 drivers/tty/n_tty.c:2339
1 lock held by syz.0.588/7823:
 #0: ffff88802ad07128 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock+0x1c/0x50 include/linux/mmap_lock.h:117
1 lock held by syz.1.587/7816:
1 lock held by syz.1.587/7817:
 #0: ffff88802ad00f28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock+0x1c/0x50 include/linux/mmap_lock.h:117
1 lock held by syz.1.587/7820:
 #0: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1f30 drivers/net/tun.c:3066
2 locks held by dhcpcd-run-hook/7824:
8 locks held by syz.9.590/7829:
 #0: ffff88807935f770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff888077988460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff888059ae7488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x500 fs/kernfs/file.c:287
 #3: ffff88802561a490 (kn->active#652){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x1fd/0x500 fs/kernfs/file.c:288
 #4: ffffffff8cf514a8 (serio_mutex){+.+.}-{3:3}, at: drvctl_store+0x2a/0xae0 drivers/input/serio/serio.c:388
 #5: ffff888148e39378 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:809 [inline]
 #5: ffff888148e39378 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1064 [inline]
 #5: ffff888148e39378 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa1/0x710 drivers/base/dd.c:1279
 #6: ffff888148e391d8 (&serio->drv_mutex){+.+.}-{3:3}, at: serio_disconnect_driver drivers/input/serio/serio.c:67 [inline]
 #6: ffff888148e391d8 (&serio->drv_mutex){+.+.}-{3:3}, at: serio_driver_remove+0x2a/0xa0 drivers/input/serio/serio.c:785
 #7: ffffffff8cf56808 (input_mutex){+.+.}-{3:3}, at: __input_unregister_device+0x10e/0x320 drivers/input/input.c:2280

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

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 09/16/2026
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>