INFO: task syz-executor2:12665 blocked for more than 120 seconds.
      Not tainted 4.9.67-gf26d3c7 #106
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D29328 12665   3467 0x00000004
 ffff8801d10b4800 ffff8801d5356f40 ffff8801c6044a80 ffff8801d6bf9800
 ffff8801db221418 ffff8801c71ff7d0 ffffffff838981cb ffff8801c71ff7a8
 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
 [<ffffffff8156cb20>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff8156cb20>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff8156cdd4>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff8156cef6>] do_readv+0xe6/0x250 fs/read_write.c:924
 [<ffffffff815703e7>] SYSC_readv fs/read_write.c:1011 [inline]
 [<ffffffff815703e7>] SyS_readv+0x27/0x30 fs/read_write.c:1008
 [<ffffffff838a9985>] entry_SYSCALL_64_fastpath+0x23/0xc6

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/3236:
 #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-executor2/12665:
 #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 #106
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d884fd00 ffffffff81d906e9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba170 ffff8801d884fd38
 ffffffff81d9b80d 0000000000000001 0000000000000000 ffff8801d6c56418
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: 12653 Comm: syz-executor2 Not tainted 4.9.67-gf26d3c7 #106
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d1549800 task.stack: ffff8801d8c90000
RIP: 0010:[<ffffffff813681e7>] 
c [<ffffffff813681e7>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff813681e7>] 
c [<ffffffff813681e7>] __sanitizer_cov_trace_pc+0x27/0x60 kernel/kcov.c:67
RSP: 0018:ffff8801d8c97b28  EFLAGS: 00000246
RAX: ffff8801d1549800 RBX: ffffc90000146060 RCX: ffffc90000e82000
RDX: 0000000000000001 RSI: 00000000eb35c362 RDI: ffffc90000147260
RBP: ffff8801d8c97b28 R08: 1ffff1003a2a941a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d1549800 R12: ffffc90000145000
R13: 0000000558f39914 R14: 0000000020a80000 R15: ffff8801c9185738
FS:  00007f57ba3ae700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000b6d8d8 CR3: 00000001a39be000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d8c97b78
c ffffffff81fff176
c ffffffffffffeff9
c 0000000000000914
c
 0000000000000000
c ffff8801c9185500
c 1ffff1003b192f75
c 000000000000541b
c
 ffffffffffffffe7
c ffff8801d0ab1800
c ffff8801d8c97d70
c ffffffff81ff7e93
c
Call Trace:
 [<ffffffff81fff176>] inq_canon drivers/tty/n_tty.c:2414 [inline]
 [<ffffffff81fff176>] n_tty_ioctl+0x266/0x2d0 drivers/tty/n_tty.c:2431
 [<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
 [<ffffffff815ab5bf>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab5bf>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838a9985>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
c00 
c0f 
c1f 
c00 
c55 
c65 
c48 
c8b 
c04 
c25 
c40 
c55 
c01 
c00 
c48 
c85 
cc0 
c48 
c89 
ce5 
c74 
c1a 
c65 
c8b 
c15 
cf7 
cd2 
cca 
c7e 
c81 
ce2 
c00 
c01 
c1f 
c00 
c75 
c0b 
c8b 
c90 
c68 
c12 
c00 
c00 
c<83> 
cfa 
c01 
c74 
c02 
c5d 
cc3 
c48 
c8b 
c88 
c70 
c12 
c00 
c00 
c8b 
c80 
c6c 
c12 
c00 
c00 
c48 
c