INFO: task syz-executor1:5078 blocked for more than 120 seconds.
      Not tainted 4.9.70-gc14c7b3 #110
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D28800  5078   3562 0x00000006
 ffff8801cd823000 ffff8801c42f0000 ffff8801c42f0000 ffff8801c042e000
 ffff8801db321458 ffff8801cd967768 ffffffff83898c3b ffff8801cd967740
 ffffffff8123886f 00ffffff838a4b36 ffff8801db321d28 ffff8801db321d50
Call Trace:
 [<ffffffff8389a1df>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a4d0f>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff838a4d0f>] rwsem_down_write_failed+0x50f/0x960 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81dc3e07>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff838a34fc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff838a34fc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff81fff991>] n_tty_flush_buffer+0x21/0x320 drivers/tty/n_tty.c:359
 [<ffffffff8200d737>] tty_ldisc_hangup+0x87/0x5b0 drivers/tty/tty_ldisc.c:709
 [<ffffffff81ff4638>] __tty_hangup.part.23+0x5e8/0xaf0 drivers/tty/tty_io.c:736
 [<ffffffff81ff4b61>] __tty_hangup drivers/tty/tty_io.c:694 [inline]
 [<ffffffff81ff4b61>] tty_vhangup+0x21/0x30 drivers/tty/tty_io.c:808
 [<ffffffff82015004>] pty_close+0x374/0x4c0 drivers/tty/pty.c:74
 [<ffffffff81ff6839>] tty_release+0x369/0xfb0 drivers/tty/tty_io.c:1796
 [<ffffffff81571b8c>] __fput+0x28c/0x6e0 fs/file_table.c:208
 [<ffffffff81572065>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff81193685>] task_work_run+0x115/0x190 kernel/task_work.c:116
 [<ffffffff811646f0>] get_signal+0x11b0/0x14e0 kernel/signal.c:2145
 [<ffffffff81052c87>] do_signal+0x87/0x1a00 arch/x86/kernel/signal.c:807
 [<ffffffff81003a31>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:156
 [<ffffffff81006340>] prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline]
 [<ffffffff81006340>] syscall_return_slowpath+0x1a0/0x1e0 arch/x86/entry/common.c:259
 [<ffffffff838aa4a6>] entry_SYSCALL_64_fastpath+0xc4/0xc6

Showing all locks held in the system:
2 locks held by khungtaskd/513:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe45>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe45>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff812355e0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3301:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8602>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff820022a4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
4 locks held by syz-executor1/5078:
 #0:  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff8201218a>] tty_lock+0x6a/0xe0 drivers/tty/tty_mutex.c:18
 #1:  (&tty->legacy_mutex/1){+.+...}, at: [<ffffffff8201218a>] tty_lock+0x6a/0xe0 drivers/tty/tty_mutex.c:18
 #2:  (&tty->ldisc_sem){++++++}, at: [<ffffffff8200c47b>] tty_ldisc_ref+0x1b/0x80 drivers/tty/tty_ldisc.c:294
 #3:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff81fff991>] n_tty_flush_buffer+0x21/0x320 drivers/tty/n_tty.c:359
3 locks held by syz-executor1/5126:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8602>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff820022a4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
 #2:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff820022c7>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137

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

NMI backtrace for cpu 0
CPU: 0 PID: 513 Comm: khungtaskd Not tainted 4.9.70-gc14c7b3 #110
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d89efd00 ffffffff81d90c49 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810ba1a0 ffff8801d89efd38
 ffffffff81d9bd6d 0000000000000000 0000000000000000 ffff8801cdf68418
Call Trace:
 [<ffffffff81d90c49>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90c49>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9bd6d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9bea7>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba294>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81370410>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81370410>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81370410>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81370410>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811985ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838aa6aa>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5121 Comm: syz-executor1 Not tainted 4.9.70-gc14c7b3 #110
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cdf6c800 task.stack: ffff8801cdb48000
RIP: 0010:[<ffffffff813681f6>] 
c [<ffffffff813681f6>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff813681f6>] 
c [<ffffffff813681f6>] check_kcov_mode kernel/kcov.c:68 [inline]
RIP: 0010:[<ffffffff813681f6>] 
c [<ffffffff813681f6>] __sanitizer_cov_trace_pc+0x26/0x50 kernel/kcov.c:100
RSP: 0018:ffff8801cdb4fb28  EFLAGS: 00000246
RAX: ffff8801cdf6c800 RBX: ffffc90004c4c060 RCX: ffffffff81fff69c
RDX: 0000000000000002 RSI: ffffc900013eb000 RDI: ffffc90004c4d260
RBP: ffff8801cdb4fb28 R08: 1ffff10039beda1a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801cdf6c800 R12: ffffc90004c4b000
R13: 000000084da1040e R14: 000000002097dffc R15: ffff8801cd91acb8
FS:  00007fa7e416b700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f59d8455000 CR3: 00000001d547f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801cdb4fb78
c ffffffff81fff69c
c ffffffffffffffff
c 000000000000040d
c
 0000000000000000
c ffff8801cd91aa80
c 1ffff10039b69f75
c 000000000000541b
c
 ffffffffffffffe7
c ffff8801cee37e00
c ffff8801cdb4fd70
c ffffffff81ff8413
c
Call Trace:
 [<ffffffff81fff69c>] inq_canon drivers/tty/n_tty.c:2411 [inline]
 [<ffffffff81fff69c>] n_tty_ioctl+0x20c/0x2d0 drivers/tty/n_tty.c:2431
 [<ffffffff81ff8413>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aaa0a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aaa0a>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815aba2f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815aba2f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838aa405>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
c00 
c00 
c0f 
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c00 
c55 
c48 
c89 
ce5 
c65 
c48 
c8b 
c04 
c25 
c40 
c55 
c01 
c00 
c65 
c8b 
c15 
cec 
cd2 
cca 
c7e 
c81 
ce2 
c00 
c01 
c1f 
c00 
c48 
c8b 
c4d 
c08 
c75 
c2b 
c8b 
c90 
c68 
c12 
c00 
c00 
c<83> 
cfa 
c02 
c75 
c20 
c48 
c8b 
cb0 
c70 
c12 
c00 
c00 
c8b 
c80 
c6c 
c12 
c00 
c00 
c48 
c8b 
c16 
c