INFO: task syz-executor3:16317 blocked for more than 120 seconds.
      Not tainted 4.9.72-gcb7518e #10
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor3   D29264 16317   3526 0x20020004
 ffff8801d9993000 ffff8801c4004fc0 ffff8801d8f79500 ffff8801b5e9e000
 ffff8801db221458 ffff8801c304f6a0 ffffffff8389e5fb ffff8801c304f678
 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
 [<ffffffff8200f7a5>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
 [<ffffffff82010651>] tty_mode_ioctl+0x931/0x9c0 drivers/tty/tty_ioctl.c:970
 [<ffffffff82010780>] n_tty_ioctl_helper+0x40/0x360 drivers/tty/tty_ioctl.c:1161
 [<ffffffff82004348>] n_tty_ioctl+0x148/0x2d0 drivers/tty/n_tty.c:2437
 [<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
 [<ffffffff8167ab0a>] C_SYSC_ioctl fs/compat_ioctl.c:1624 [inline]
 [<ffffffff8167ab0a>] compat_SyS_ioctl+0x4da/0x2050 fs/compat_ioctl.c:1549
 [<ffffffff81006fc7>] do_syscall_32_irqs_on arch/x86/entry/common.c:322 [inline]
 [<ffffffff81006fc7>] do_fast_syscall_32+0x2f7/0x890 arch/x86/entry/common.c:384
 [<ffffffff838b0be1>] entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124

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/3296:
 #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 locks held by syz-executor3/16317:
 #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 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.72-gcb7518e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d996fd00 ffffffff81d922b9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810ba190 ffff8801d996fd38
 ffffffff81d9d3dd 0000000000000000 0000000000000000 ffff8801d88e3418
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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16300 Comm: syz-executor3 Not tainted 4.9.72-gcb7518e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8bf4800 task.stack: ffff8801d9298000
RIP: 0010:[<ffffffff8136945f>] 
c [<ffffffff8136945f>] __sanitizer_cov_trace_pc+0x3f/0x50 kernel/kcov.c:105
RSP: 0018:ffff8801d929fa88  EFLAGS: 00000216
RAX: 0000000000010000 RBX: ffffc900066d6060 RCX: ffffffff8200440c
RDX: 0000000000010000 RSI: ffffc90001290000 RDI: ffffc900066d7260
RBP: ffff8801d929fa88 R08: 1ffff1003b17ea1a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d8bf4800 R12: ffffc900066d5000
R13: 0000000591d922c7 R14: 0000000020913000 R15: ffff8801d888dfb8
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f6f67b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000001b95358 CR3: 00000001c3691000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d929fad8
c ffffffff8200440c
c ffffffffffffffff
c 00000000000002c6
c
 0000000000000000
c ffff8801d888dd80
c 1ffff1003b253f61
c 000000000000541b
c
 ffffffffffffffe7
c ffff8801c5cf1400
c ffff8801d929fcd0
c ffffffff81ffd153
c
Call Trace:
 [<ffffffff8200440c>] inq_canon drivers/tty/n_tty.c:2411 [inline]
 [<ffffffff8200440c>] n_tty_ioctl+0x20c/0x2d0 drivers/tty/n_tty.c:2431
 [<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
 [<ffffffff8167ab0a>] C_SYSC_ioctl fs/compat_ioctl.c:1624 [inline]
 [<ffffffff8167ab0a>] compat_SyS_ioctl+0x4da/0x2050 fs/compat_ioctl.c:1549
 [<ffffffff81006fc7>] do_syscall_32_irqs_on arch/x86/entry/common.c:322 [inline]
 [<ffffffff81006fc7>] do_fast_syscall_32+0x2f7/0x890 arch/x86/entry/common.c:384
 [<ffffffff838b0be1>] entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
Code: 
c81 
ce2 
c00 
c01 
c1f 
c00 
c48 
c8b 
c4d 
c08 
c75 
c2b 
c8b 
c90 
c68 
c12 
c00 
c00 
c83 
cfa 
c02 
c75 
c20 
c48 
c8b 
cb0 
c70 
c12 
c00 
c00 
c8b 
c80 
c6c 
c12 
c00 
c00 
c48 
c8b 
c16 
c48 
c83 
cc2 
c01 
c<48> 
c39 
cd0 
c76 
c07 
c48 
c89 
c0c 
cd6 
c48 
c89 
c16 
c5d 
cc3 
c0f 
c1f 
c00 
c55 
c48 
c89 
ce5 
c