TCP: request_sock_TCPv6: Possible SYN flooding on port 2. Sending cookies.  Check SNMP counters.
INFO: rcu_sched self-detected stall on CPU
	0-....: (124999 ticks this GP) idle=932/1/4611686018427387906 softirq=34594/34594 fqs=31227 
	 (t=125000 jiffies g=19397 c=19396 q=942)
NMI backtrace for cpu 0
CPU: 0 PID: 10371 Comm: syz-executor7 Not tainted 4.18.0-rc2+ #119
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+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 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:156 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1336
 print_cpu_stall kernel/rcu/tree.c:1485 [inline]
 check_cpu_stall.isra.60.cold.78+0x36c/0x5a6 kernel/rcu/tree.c:1553
 __rcu_pending kernel/rcu/tree.c:3244 [inline]
 rcu_pending kernel/rcu/tree.c:3291 [inline]
 rcu_check_callbacks+0x23f/0xcd0 kernel/rcu/tree.c:2646
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x3eb/0x10c0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x2f3/0x750 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x165/0x730 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
RIP: 0010:check_kcov_mode kernel/kcov.c:67 [inline]
RIP: 0010:write_comp_data+0x1b/0x70 kernel/kcov.c:122
Code: 00 e9 76 fc ff ff e8 74 27 cb ff 90 90 90 90 55 65 4c 8b 04 25 40 ee 01 00 65 8b 05 bf e1 85 7e 48 89 e5 a9 00 01 1f 00 75 51 <41> 8b 80 90 12 00 00 83 f8 03 75 45 49 8b 80 98 12 00 00 45 8b 80 
RSP: 0018:ffff88019df0f7a0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 000000023c1863f9 RCX: ffffffff83a4604c
RDX: 0000000000000000 RSI: 00000000000000ff RDI: 0000000000000001
RBP: ffff88019df0f7a0 R08: ffff88019a470780 R09: 0000000000000006
R10: ffff88019a470780 R11: 0000000000000000 R12: ffffc9000345f000
R13: 0000000000000103 R14: 000000023c1863fa R15: 0000000000000000
 __sanitizer_cov_trace_const_cmp1+0x1a/0x20 kernel/kcov.c:174
 __process_echoes+0x2dc/0x8d0 drivers/tty/n_tty.c:732
 flush_echoes drivers/tty/n_tty.c:799 [inline]
 __receive_buf drivers/tty/n_tty.c:1615 [inline]
 n_tty_receive_buf_common+0x11dd/0x2c60 drivers/tty/n_tty.c:1709
 n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1738
 tiocsti drivers/tty/tty_io.c:2180 [inline]
 tty_ioctl+0x7e7/0x1870 drivers/tty/tty_io.c:2566
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a99
Code: 1d ba 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007f1efc17bc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1efc17c6d4 RCX: 0000000000455a99
RDX: 0000000020000140 RSI: 0000000000005412 RDI: 0000000000000016
RBP: 000000000072bff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004be97b R14: 00000000004cd6c8 R15: 0000000000000002