INFO: task syz-executor2:4546 blocked for more than 120 seconds.
      Not tainted 4.9.70-gc14c7b3 #6
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D29024  4546   3576 0x20020004
 ffff8801d5b88000 ffff8801d2249f80 ffff8801d567aa00 ffff8801d54d9800
 ffff8801db321458 ffff8801d6a1f6a0 ffffffff83898c3b ffff8801d6a1f678
 ffffffff8123886f 00ffffff838a45aa ffff8801db321d28 ffff8801db321d50
Call Trace:
 [<ffffffff8389a1df>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a46c0>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc3dd8>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff838a3442>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff838a3442>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff8200aa35>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
 [<ffffffff8200b8e1>] tty_mode_ioctl+0x931/0x9c0 drivers/tty/tty_ioctl.c:970
 [<ffffffff8200ba10>] n_tty_ioctl_helper+0x40/0x360 drivers/tty/tty_ioctl.c:1161
 [<ffffffff81fff5d8>] n_tty_ioctl+0x148/0x2d0 drivers/tty/n_tty.c:2437
 [<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
 [<ffffffff8167970a>] C_SYSC_ioctl fs/compat_ioctl.c:1624 [inline]
 [<ffffffff8167970a>] 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
 [<ffffffff838aba61>] 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: [<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/3305:
 #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 locks held by syz-executor2/4546:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8602>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff8200aa35>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592

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

NMI backtrace for cpu 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.70-gc14c7b3 #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d89c7d00 ffffffff81d90c49 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810ba1a0 ffff8801d89c7d38
 ffffffff81d9bd6d 0000000000000000 0000000000000000 ffff8801d5feb418
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: 4510 Comm: syz-executor2 Not tainted 4.9.70-gc14c7b3 #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d5561800 task.stack: ffff8801d4eb8000
RIP: 0010:[<ffffffff81fff697>] 
c [<ffffffff81fff697>] inq_canon drivers/tty/n_tty.c:2408 [inline]
RIP: 0010:[<ffffffff81fff697>] 
c [<ffffffff81fff697>] n_tty_ioctl+0x207/0x2d0 drivers/tty/n_tty.c:2431
RSP: 0018:ffff8801d4ebfa98  EFLAGS: 00000293
RAX: ffff8801d5561800 RBX: ffffc90000b70060 RCX: ffffffff81fff6f6
RDX: 0000000000000000 RSI: 00000000f9883016 RDI: ffffc90000b71260
RBP: ffff8801d4ebfad8 R08: 1ffff1003aaac41a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d5561800 R12: ffffc90000b6f000
R13: 00000008e76bd9f3 R14: 0000000020fe9000 R15: ffff8801d57e3db8
FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f776bb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000c420017000 CR3: 00000001d66fb000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffffffffefce
c 00000000000009f2
c 0000000000000000
c ffff8801d57e3b80
c
 1ffff1003a9d7f61
c 000000000000541b
c ffffffffffffffe7
c ffff8801d266a800
c
 ffff8801d4ebfcd0
c ffffffff81ff8413
c ffff8801d5561800
c ffffffff81fff490
c
Call Trace:
 [<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
 [<ffffffff8167970a>] C_SYSC_ioctl fs/compat_ioctl.c:1624 [inline]
 [<ffffffff8167970a>] 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
 [<ffffffff838aba61>] entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
Code: 
c8b 
cac 
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cff 
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c00 
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c<e8> 
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c36 
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c89 
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cff 
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c00 
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c48 
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cc8 
c