INFO: task syz-executor688:2175 blocked for more than 140 seconds.
      Not tainted 4.9.135+ #117
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor688 D29976  2175      1 0x00000000
 ffff8801cb57df00 ffff8801cb4e5d80 ffff8801cb4e5d80 ffff8801cb5797c0
 ffff8801db721018 ffff8801cacf7840 ffffffff82806912 0000000000000000
 ffffffff83cc4350 0000000000000000 00000000000044ad ffff8801db7218f0
Call Trace:
 [<ffffffff82807e3f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff828135e5>] schedule_timeout+0x735/0xe20 kernel/time/timer.c:1771
 [<ffffffff81d42f5c>] down_read_failed drivers/tty/tty_ldsem.c:241 [inline]
 [<ffffffff81d42f5c>] __ldsem_down_read_nested+0x33c/0x610 drivers/tty/tty_ldsem.c:332
 [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 [<ffffffff81d3c8b5>] tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:275
 [<ffffffff81d28286>] tty_ioctl+0x3b6/0x2190 drivers/tty/tty_io.c:3009
 [<ffffffff81546ddc>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff81546ddc>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff81546ddc>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff81547e5f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff81547e5f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82816b93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bb4c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bb4c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe314>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/1893:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8156cc6c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/2021:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor688/2172:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2175:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2208:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2211:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2233:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2235:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2238:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor688/2257:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2259:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2287:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2289:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2372:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2375:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2397:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2399:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2427:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2429:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2444:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2447:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2463:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2465:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2480:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2483:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2523:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2525:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2567:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2569:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2591:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2593:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2608:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2611:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2621:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2623:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2651:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2653:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2682:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2684:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2712:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2714:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2736:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2738:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2760:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2762:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2790:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2792:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2814:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2816:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2838:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2840:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2873:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2876:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2897:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2900:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2924:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2926:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/2978:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/2980:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3002:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/3004:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3020:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/3022:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3062:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/3064:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3098:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor688/3121:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/3124:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3151:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/3154:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3176:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor688/3178:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
1 lock held by syz-executor688/3210:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor688/3211:
 #0:  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81d4205a>] tty_lock+0x6a/0xd0 drivers/tty/tty_mutex.c:18
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814ca2>] ldsem_down_write+0x32/0x37 drivers/tty/tty_ldsem.c:393
2 locks held by syz-executor688/3212:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814c62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d36fc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.135+ #117
 ffff8801d9907d08 ffffffff81b42b89 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff81098330 ffff8801d9907d40
 ffffffff81b4dc99 0000000000000000 0000000000000000 0000000000000004
Call Trace:
 [<ffffffff81b42b89>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42b89>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4dc99>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4dc2c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff81098434>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c0dd>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c0dd>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c0dd>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c0dd>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff811428dd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82816d5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff828157a6