INFO: task syz-executor1:6594 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-executor1   D29152  6594   3582 0x20020004
 ffff8801c6c20000 0000000000000000 ffff8801b4d14000 ffff8801da2cb000
 ffff8801db321458 ffff8801c46976a0 ffffffff8389e5fb ffff8801c4697678
 ffffffff8123940f 00ffffff838a9f6a ffff8801db321d28 ffff8801db321d50
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/3301:
 #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-executor1/6594:
 #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 4.9.72-gcb7518e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9b77d00 ffffffff81d922b9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba190 ffff8801d9b77d38
 ffffffff81d9d3dd 0000000000000001 0000000000000000 ffff8801b4eeb418
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: 6595 Comm: syz-executor1 Not tainted 4.9.72-gcb7518e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c6c21800 task.stack: ffff8801c4648000
RIP: 0010:[<ffffffff8136942d>] 
c [<ffffffff8136942d>] get_current arch/x86/include/asm/current.h:14 [inline]
RIP: 0010:[<ffffffff8136942d>] 
c [<ffffffff8136942d>] __sanitizer_cov_trace_pc+0xd/0x50 kernel/kcov.c:99
RSP: 0018:ffff8801c464fa88  EFLAGS: 00000293
RAX: ffff8801c6c21800 RBX: ffffc90006012060 RCX: ffffffff82004466
RDX: 0000000000010000 RSI: ffffc9000394d000 RDI: ffffc90006013260
RBP: ffff8801c464fa88 R08: 1ffff10038d8441a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801c6c21800 R12: ffffc90006011000
R13: 00000003a1de2cba R14: 0000000020e4dffc R15: ffff8801c4bc5fb8
FS:  0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:00000000f6eb3b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000001e96f48 CR3: 00000001c4790000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801c464fad8
c ffffffff8200440c
c ffffffffffffeffa
c 0000000000000cb9
c
 0000000000000000
c ffff8801c4bc5d80
c 1ffff100388c9f61
c 000000000000541b
c
 ffffffffffffffe7
c ffff8801c499da00
c ffff8801c464fcd0
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: 
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c<65> 
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c