INFO: task syz-executor7:6351 blocked for more than 120 seconds.
      Not tainted 4.9.70-g9542d2a #109
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D28336  6351   3541 0x00000004
 ffff8801d1ce9800 ffff8801c31ff9c0 ffff8801ce6fd500 ffff8801d5093000
 ffff8801db221418 ffff8801c5dff7d0 ffffffff83898c3b ffff8801c5dff7a8
 ffffffff8123886f 00ffffff838a45aa ffff8801db221ce8 ffff8801db221d10
Call Trace:
 [<ffffffff8389a1df>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a46c0>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc3bb8>] 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
 [<ffffffff820020a7>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137
 [<ffffffff81ff08f9>] tty_read+0x169/0x250 drivers/tty/tty_io.c:1079
 [<ffffffff81568ef1>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff8156cd60>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff8156cd60>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff8156d014>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff8156d136>] do_readv+0xe6/0x250 fs/read_write.c:924
 [<ffffffff81570627>] SYSC_readv fs/read_write.c:1011 [inline]
 [<ffffffff81570627>] SyS_readv+0x27/0x30 fs/read_write.c:1008
 [<ffffffff838aa405>] entry_SYSCALL_64_fastpath+0x23/0xc6

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe15>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe15>] 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: [<ffffffff82002084>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor7/6351:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a8602>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82002084>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
 #2:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff820020a7>] n_tty_read+0x217/0x16c0 drivers/tty/n_tty.c:2137

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

NMI backtrace for cpu 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.70-g9542d2a #109
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8e7fd00 ffffffff81d90a29 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810ba1a0 ffff8801d8e7fd38
 ffffffff81d9bb4d 0000000000000000 0000000000000000 ffff8801ca5e3418
Call Trace:
 [<ffffffff81d90a29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d90a29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9bb4d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9bc87>] 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
 [<ffffffff813703e0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813703e0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813703e0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813703e0>] 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: 6319 Comm: syz-executor7 Not tainted 4.9.70-g9542d2a #109
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cec28000 task.stack: ffff8801cec30000
RIP: 0010:[<ffffffff81fff488>] 
c [<ffffffff81fff488>] variable_test_bit arch/x86/include/asm/bitops.h:318 [inline]
RIP: 0010:[<ffffffff81fff488>] 
c [<ffffffff81fff488>] inq_canon drivers/tty/n_tty.c:2411 [inline]
RIP: 0010:[<ffffffff81fff488>] 
c [<ffffffff81fff488>] n_tty_ioctl+0x218/0x2d0 drivers/tty/n_tty.c:2431
RSP: 0018:ffff8801cec37b38  EFLAGS: 00000206
RAX: 0000000000000ad7 RBX: ffffc90005668060 RCX: ffffc900010ff000
RDX: 0000000000010000 RSI: 00000000294c7bd1 RDI: ffffc90005669260
RBP: ffff8801cec37b78 R08: 1ffff10039d8511a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801cec28000 R12: ffffc90005667000
R13: 000000058fa29ad7 R14: 00000000205b2000 R15: ffff8801cec1bdb8
FS:  00007f3c689b9700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000013483e0 CR3: 00000001b8274000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffffffffffff
c 0000000000000ad6
c 0000000000000000
c ffff8801cec1bb80
c
 1ffff10039d86f75
c 000000000000541b
c ffffffffffffffe7
c ffff8801ce6f9800
c
 ffff8801cec37d70
c ffffffff81ff81f3
c ffff8801cec28000
c ffffffff81fff270
c
Call Trace:
 [<ffffffff81ff81f3>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aa7da>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa7da>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815ab7ff>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab7ff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838aa405>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
cff 
cff 
ce8 
c6c 
c8d 
c36 
cff 
c48 
c8b 
c45 
cd0 
c49 
c8d 
c9c 
c24 
c60 
c10 
c00 
c00 
c4c 
c29 
ce8 
c48 
c89 
c45 
cc0 
ce8 
c54 
c8d 
c36 
cff 
c4c 
c89 
ce8 
c25 
cff 
c0f 
c00 
c00 
c48 
c0f 
ca3 
c03 
c<48> 
c89 
c45 
cc8 
c73 
c43 
ce8 
c3d 
c8d 
c36 
cff 
c48 
c8b 
c45 
cc8 
c48 
cbe 
c00 
c00 
c00 
c00 
c