TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=35a/1/0x4000000000000002 softirq=359312/359313 fqs=5248 
rcu: 	 (t=10502 jiffies g=545609 q=1462)
NMI backtrace for cpu 1
CPU: 1 PID: 1910 Comm: syz-executor3 Not tainted 4.20.0+ #362
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d3/0x2c6 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1c2/0x22c lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x16f/0x1bc kernel/rcu/tree.c:1211
 print_cpu_stall.cold.68+0x218/0x40a kernel/rcu/tree.c:1348
 check_cpu_stall kernel/rcu/tree.c:1422 [inline]
 rcu_pending kernel/rcu/tree.c:3018 [inline]
 rcu_check_callbacks+0xac1/0x1410 kernel/rcu/tree.c:2521
 update_process_times+0x2d/0x70 kernel/time/timer.c:1635
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:161
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1271
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x41c/0x10d0 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x313/0x780 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline]
 smp_apic_timer_interrupt+0x1a1/0x760 arch/x86/kernel/apic/apic.c:1060
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:67 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x11/0x50 kernel/kcov.c:101
Code: 7c 10 e0 4a 89 74 10 e8 4a 89 54 10 f0 4a 89 4c d8 20 4c 89 08 5d c3 66 90 55 48 89 e5 48 8b 75 08 65 48 8b 04 25 40 ee 01 00 <65> 8b 15 c8 47 80 7e 81 e2 00 01 1f 00 75 2b 8b 90 d8 12 00 00 83
RSP: 0018:ffff88805f507338 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff88809dedc100 RBX: ffff8880885be4c0 RCX: ffffffff86c1b966
RDX: 0000000000000000 RSI: ffffffff86c1b983 RDI: 0000000000000004
RBP: ffff88805f507338 R08: ffff88809dedc100 R09: 0000000000000008
R10: 0000000000000003 R11: ffff88809dedc100 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 xfrm_policy_insert_list+0x233/0x1020 net/xfrm/xfrm_policy.c:1531
 xfrm_policy_inexact_insert+0x166/0xee0 net/xfrm/xfrm_policy.c:1195
 xfrm_policy_insert+0x639/0x850 net/xfrm/xfrm_policy.c:1570
 pfkey_spdadd+0x10f8/0x19d0 net/key/af_key.c:2339
 pfkey_process+0x851/0x9a0 net/key/af_key.c:2844
 pfkey_sendmsg+0x5df/0xfb0 net/key/af_key.c:3683
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
 __sys_sendmsg+0x11d/0x280 net/socket.c:2154
 __do_sys_sendmsg net/socket.c:2163 [inline]
 __se_sys_sendmsg net/socket.c:2161 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4579b9
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc2cc281c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004579b9
RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc2cc2826d4
R13: 00000000004c4d47 R14: 00000000004d84c0 R15: 00000000ffffffff