INFO: task syz-executor3:15931 blocked for more than 140 seconds.
      Not tainted 4.9.126+ #90
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor3   D29448 15931   2092 0x00000004
 ffff88019f1217c0 ffff8801d6240b00 ffff8801cbb22680 ffff8801a038c740
 ffff8801db721018 ffff8801a1b177b0 ffffffff8277d952 0000000000000000
 ffff88019f1217c0 ffffffff810ec84a 00fffc0000000000 ffff8801db7218f0
Call Trace:
 [<ffffffff8277ee7f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff8223087c>] __lock_sock+0x13c/0x250 net/core/sock.c:2035
 [<ffffffff82230a86>] lock_sock_nested+0xf6/0x120 net/core/sock.c:2505
 [<ffffffff82668f50>] lock_sock include/net/sock.h:1404 [inline]
 [<ffffffff82668f50>] do_ipv6_setsockopt.isra.4+0x260/0x2e20 net/ipv6/ipv6_sockglue.c:166
 [<ffffffff8266bba7>] ipv6_setsockopt+0x97/0x130 net/ipv6/ipv6_sockglue.c:917
 [<ffffffff8245b428>] tcp_setsockopt+0x88/0xe0 net/ipv4/tcp.c:2758
 [<ffffffff8222acfa>] sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
 [<ffffffff822285f6>] SYSC_setsockopt net/socket.c:1785 [inline]
 [<ffffffff822285f6>] SyS_setsockopt+0x166/0x260 net/socket.c:1764
 [<ffffffff8100554f>] do_syscall_64+0x19f/0x480 arch/x86/entry/common.c:282
 [<ffffffff8278ca53>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81309d0c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81309d0c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813e6e4c>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2019:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff8278ab22>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81cdd9a2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.126+ #90
 ffff8801d9907d08 ffffffff81af1049 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810967d0 ffff8801d9907d40
 ffffffff81afbda9 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81af1049>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81af1049>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81afbda9>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81afbd3c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810968d4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8130a29d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8130a29d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8130a29d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8130a29d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff8113dc9d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8278cc1c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6908 Comm: syz-executor2 Not tainted 4.9.126+ #90
task: ffff88019fec2f80 task.stack: ffff8801d4db0000
RIP: 0033:[<00000000004023c4>] 
c [<00000000004023c4>] 0x4023c4
RSP: 002b:00007f5d8ec80690  EFLAGS: 00000282
RAX: 00000000b708a9fe RBX: 000000000000000b RCX: 00000000004572a9
RDX: 0000000000000000 RSI: 00007f5d8ec806c0 RDI: 000000000000000b
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d7288 R14: 00000000004ca390 R15: 0000000000000000
FS:  00007f5d8ec81700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4db4ab1000 CR3: 00000001d5dc1000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400