TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
invalid inflight: 1 state 5 cwnd 10 mss 21845
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7 at net/ipv4/tcp_output.c:2507 tcp_send_loss_probe.cold+0x83/0xa2 net/ipv4/tcp_output.c:2507
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.14.145 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x197 lib/dump_stack.c:53
 panic+0x1f2/0x426 kernel/panic.c:182
 __warn.cold+0x2f/0x36 kernel/panic.c:546
 report_bug+0x216/0x254 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 fixup_bug arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x1bb/0x310 arch/x86/kernel/traps.c:295
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963
RIP: 0010:tcp_send_loss_probe.cold+0x83/0xa2 net/ipv4/tcp_output.c:2507
RSP: 0018:ffff8880a9cefb60 EFLAGS: 00010282
RAX: 000000000000002d RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000100 RSI: ffffffff869d2f80 RDI: ffffed101539df62
RBP: ffff8880a9cefb90 R08: 000000000000002d R09: ffff8880a9ce2a88
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88806080eec0
R13: 0000000000000001 R14: 0000000000005555 R15: 000000000000000a
 tcp_write_timer_handler+0x4a8/0x7e0 net/ipv4/tcp_timer.c:575
 tcp_write_timer+0xd8/0x180 net/ipv4/tcp_timer.c:597
 call_timer_fn+0x161/0x670 kernel/time/timer.c:1279
 expire_timers kernel/time/timer.c:1318 [inline]
 __run_timers kernel/time/timer.c:1634 [inline]
 __run_timers kernel/time/timer.c:1602 [inline]
 run_timer_softirq+0x5b4/0x1570 kernel/time/timer.c:1647
 __do_softirq+0x244/0x9a0 kernel/softirq.c:288
 run_ksoftirqd kernel/softirq.c:670 [inline]
 run_ksoftirqd+0x8c/0x1b0 kernel/softirq.c:662
 smpboot_thread_fn+0x5f4/0x960 kernel/smpboot.c:164
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Kernel Offset: disabled
Rebooting in 86400 seconds..