INFO: task syz-executor1:18481 blocked for more than 120 seconds.
      Not tainted 4.9.67-gf26d3c7 #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D29456 18481   3551 0x20020004
 ffff8801cb266000 ffff8801cf841f80 ffff8801cf841f80 ffff8801d12c6000
 ffff8801db221418 ffff8801c3bcf760 ffffffff838981cb ffff8801c3bcf738
 ffffffff8123885f 00ffffff838a3b3a ffff8801db221ce8 ffff8801db221d10
Call Trace:
 [<ffffffff8389976f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a3c50>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc3878>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff838a29d2>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff838a29d2>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff82001d47>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137
 [<ffffffff81ff0599>] tty_read+0x169/0x250 drivers/tty/tty_io.c:1079
 [<ffffffff81568cb1>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff8156dbd2>] do_loop_readv_writev fs/read_write.c:1105 [inline]
 [<ffffffff8156dbd2>] compat_do_readv_writev+0x522/0x760 fs/read_write.c:1099
 [<ffffffff8156def3>] compat_readv+0xe3/0x150 fs/read_write.c:1128
 [<ffffffff8156e054>] do_compat_readv+0xf4/0x1d0 fs/read_write.c:1148
 [<ffffffff815705c6>] C_SYSC_readv fs/read_write.c:1160 [inline]
 [<ffffffff815705c6>] compat_SyS_readv+0x26/0x30 fs/read_write.c:1156
 [<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
 [<ffffffff838aafe1>] 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: [<ffffffff8136fe05>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff812355d0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3306:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82001d24>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor1/18481:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82001d24>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
 #2:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff82001d47>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.67-gf26d3c7 #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d89bfd00 ffffffff81d906e9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba170 ffff8801d89bfd38
 ffffffff81d9b80d 0000000000000001 0000000000000000 ffff8801d0d4cc18
Call Trace:
 [<ffffffff81d906e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d906e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9b80d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9b947>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba264>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff813703d0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813703d0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813703d0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813703d0>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811985ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838a9c2a>] 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: 18445 Comm: syz-executor1 Not tainted 4.9.67-gf26d3c7 #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d12c6000 task.stack: ffff8801d6b48000
RIP: 0010:[<ffffffff813681c0>] 
c [<ffffffff813681c0>] __sanitizer_cov_trace_pc+0x0/0x60
RSP: 0018:ffff8801d6b4fa90  EFLAGS: 00000293
RAX: ffff8801d12c6000 RBX: ffffc90001b27060 RCX: 1ffff1003ad69f1c
RDX: 0000000000000000 RSI: 0000000062696dbb RDI: ffffc90001b28260
RBP: ffff8801d6b4fad8 R08: 1ffff1003a258d1a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d12c6000 R12: ffffc90001b26000
R13: 000000046ebf17a2 R14: 00000000205fe000 R15: ffff8801bdb2ceb8
FS:  0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:00000000f77e9b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007f7e81a01030 CR3: 00000001c4f95000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81fff11c
c fffffffffffffffe
c 00000000000007a1
c 0000000000000000
c
 ffff8801bdb2cc80
c 1ffff1003ad69f61
c 000000000000541b
c ffffffffffffffe7
c
 ffff8801cf5b5000
c ffff8801d6b4fcd0
c ffffffff81ff7e93
c ffff8801d12c6000
c
Call Trace:
 [<ffffffff81ff7e93>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aa59a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa59a>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff8167928a>] C_SYSC_ioctl fs/compat_ioctl.c:1624 [inline]
 [<ffffffff8167928a>] 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
 [<ffffffff838aafe1>] entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
Code: 
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c<55> 
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c48 
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c55 
c01 
c00 
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c15 
c