INFO: task syz-executor1:6146 blocked for more than 120 seconds.
      Not tainted 4.9.73-gf3f3457 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D29168  6146   3597 0x00000004
 ffff8801c97f0000 ffff8801c24a5500 ffff8801cfc33480 ffff8801c32ac800
 ffff8801db221458 ffff8801c01477d0 ffffffff8389e5fb ffff8801c01477a8
 ffffffff8123940f 00ffffff838a9f6a ffff8801db221d28 ffff8801db221d50
Call Trace:
 [<ffffffff8389fb9f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838aa080>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc5448>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff838a8e02>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff838a8e02>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff82007037>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137
 [<ffffffff81ff5859>] tty_read+0x169/0x250 drivers/tty/tty_io.c:1079
 [<ffffffff8156a4e1>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff8156e350>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff8156e350>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff8156e604>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff8156e726>] do_readv+0xe6/0x250 fs/read_write.c:924
 [<ffffffff81571c17>] SYSC_readv fs/read_write.c:1011 [inline]
 [<ffffffff81571c17>] SyS_readv+0x27/0x30 fs/read_write.c:1008
 [<ffffffff838af585>] entry_SYSCALL_64_fastpath+0x23/0xc6

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81371095>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81371095>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81236180>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3312:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838ad792>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007014>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor1/6146:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838ad792>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007014>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
 #2:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff82007037>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137
2 locks held by syz-executor1/6162:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838ad792>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff8200f7a5>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.73-gf3f3457 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8c77d00 ffffffff81d922b9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba190 ffff8801d8c77d38
 ffffffff81d9d3dd 0000000000000001 0000000000000000 ffff8801cab40418
Call Trace:
 [<ffffffff81d922b9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d922b9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9d3dd>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9d517>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba284>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81371660>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81371660>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81371660>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81371660>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119898d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838af82a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6129 Comm: syz-executor1 Not tainted 4.9.73-gf3f3457 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c9658000 task.stack: ffff8801c8348000
RIP: 0010:[<ffffffff82004407>] 
c [<ffffffff82004407>] inq_canon drivers/tty/n_tty.c:2408 [inline]
RIP: 0010:[<ffffffff82004407>] 
c [<ffffffff82004407>] n_tty_ioctl+0x207/0x2d0 drivers/tty/n_tty.c:2431
RSP: 0018:ffff8801c834fb38  EFLAGS: 00000287
RAX: 0000000000010000 RBX: ffffc90004e93060 RCX: ffffffff82004466
RDX: 0000000000010000 RSI: ffffc900040e7000 RDI: ffffc90004e94260
RBP: ffff8801c834fb78 R08: 1ffff100392cb11a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801c9658000 R12: ffffc90004e92000
R13: 000000072ce8f0a0 R14: 0000000020cdfffc R15: ffff8801c9628238
FS:  00007f9d29259700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f822674f000 CR3: 00000001c1861000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffffffffffff
c 000000000000009f
c 0000000000000000
c ffff8801c9628000
c
 1ffff10039069f75
c 000000000000541b
c ffffffffffffffe7
c ffff8801c8f63c00
c
 ffff8801c834fd70
c ffffffff81ffd153
c ffff8801c9658000
c ffffffff82004200
c
Call Trace:
 [<ffffffff81ffd153>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815abdda>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815abdda>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815acdff>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815acdff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838af585>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
c8b 
cac 
c24 
c60 
c22 
c00 
c00 
c31 
cdb 
c4c 
c39 
c6d 
cd0 
c0f 
c84 
c17 
cff 
cff 
cff 
ce8 
c2c 
c50 
c36 
cff 
c48 
c8b 
c45 
cd0 
c49 
c8d 
c9c 
c24 
c60 
c10 
c00 
c00 
c4c 
c29 
ce8 
c48 
c89 
c45 
cc0 
c<e8> 
c14 
c50 
c36 
cff 
c4c 
c89 
ce8 
c25 
cff 
c0f 
c00 
c00 
c48 
c0f 
ca3 
c03 
c48 
c89 
c45 
cc8 
c