TCP: request_sock_TCPv6: Possible SYN flooding on port 2. Sending cookies.  Check SNMP counters.
WARNING: CPU: 0 PID: 9 at include/net/sock.h:1539 sock_owned_by_me include/net/sock.h:1539 [inline]
WARNING: CPU: 0 PID: 9 at include/net/sock.h:1539 tcp_cleanup_ulp+0x1ad/0x200 net/ipv4/tcp_ulp.c:102
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 4.19.0-rc8-next-20181016+ #95
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 panic+0x2ad/0x55c kernel/panic.c:188
 __warn.cold.8+0x20/0x45 kernel/panic.c:540
kobject: 'loop2' (000000007674cfb7): kobject_uevent_env
 report_bug+0x254/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
kobject: 'loop2' (000000007674cfb7): fill_kobj_path: path = '/devices/virtual/block/loop2'
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969
RIP: 0010:sock_owned_by_me include/net/sock.h:1539 [inline]
RIP: 0010:tcp_cleanup_ulp+0x1ad/0x200 net/ipv4/tcp_ulp.c:102
Code: 83 c0 03 38 d0 7c 04 84 d2 75 61 44 8b 25 cb 4e df 02 31 ff 44 89 e6 e8 51 3d ed fa 45 85 e4 0f 84 91 fe ff ff e8 33 3c ed fa <0f> 0b e9 85 fe ff ff 4c 89 ef e8 34 84 30 fb e9 9f fe ff ff 4c 89
RSP: 0018:ffff8801d9ad66b0 EFLAGS: 00010206
RAX: ffff8801d9abe240 RBX: ffff880181a92f80 RCX: ffffffff8690e6ff
RDX: 0000000000000100 RSI: ffffffff8690e70d RDI: 0000000000000005
RBP: ffff8801d9ad66d0 R08: ffff8801d9abe240 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000003 R15: ffff8801d9ad67f0
 tcp_v4_destroy_sock+0x15c/0x980 net/ipv4/tcp_ipv4.c:1980
 tcp_v6_destroy_sock+0x15/0x20 net/ipv6/tcp_ipv6.c:1762
 inet_csk_destroy_sock+0x19f/0x440 net/ipv4/inet_connection_sock.c:838
 tcp_done+0x272/0x310 net/ipv4/tcp.c:3760
 tcp_v6_syn_recv_sock+0x1f21/0x25f0 net/ipv6/tcp_ipv6.c:1236
 tcp_get_cookie_sock+0x10e/0x580 net/ipv4/syncookies.c:213
 cookie_v6_check+0x1830/0x27d0 net/ipv6/syncookies.c:257
 tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1028 [inline]
 tcp_v6_do_rcv+0x10ea/0x13c0 net/ipv6/tcp_ipv6.c:1336
 tcp_v6_rcv+0x34e0/0x3ab0 net/ipv6/tcp_ipv6.c:1545
 ip6_input_finish+0x3fc/0x1aa0 net/ipv6/ip6_input.c:384
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip6_input+0xe4/0x600 net/ipv6/ip6_input.c:427
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x17a/0x330 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ipv6_rcv+0x110/0x630 net/ipv6/ip6_input.c:272
 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4930
 __netif_receive_skb+0x27/0x1e0 net/core/dev.c:5040
 process_backlog+0x24e/0x7a0 net/core/dev.c:5844
 napi_poll net/core/dev.c:6264 [inline]
 net_rx_action+0x7fa/0x19b0 net/core/dev.c:6330
 __do_softirq+0x308/0xb7e kernel/softirq.c:292
 run_ksoftirqd+0x5e/0x100 kernel/softirq.c:654
 smpboot_thread_fn+0x68b/0xa00 kernel/smpboot.c:164
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..