rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10500 ticks this GP) idle=886/1/0x4000000000000002 softirq=74122/74122 fqs=0 
	(t=10500 jiffies g=116957 q=977)
rcu: rcu_preempt kthread starved for 10500 jiffies! g116957 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29112    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x755/0x1580 kernel/sched/core.c:3880
 schedule+0xa8/0x270 kernel/sched/core.c:3944
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1807
 rcu_gp_fqs_loop kernel/rcu/tree.c:1611 [inline]
 rcu_gp_kthread+0x9b2/0x18c0 kernel/rcu/tree.c:1768
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 5859 Comm: syz-executor.1 Not tainted 5.3.0-rc3+ #137
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+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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+0x183/0x1cf kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2736 [inline]
 rcu_sched_clock_irq.cold+0x4dd/0xc13 kernel/rcu/tree.c:2183
 update_process_times+0x32/0x80 kernel/time/timer.c:1639
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1296
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1068 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1093
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 </IRQ>
RIP: 0010:xfrm_sk_policy_lookup+0x130/0x510 net/xfrm/xfrm_policy.c:2171
Code: 84 d2 0f 85 97 03 00 00 44 0f b7 bb 1e 02 00 00 44 89 ee 44 89 ff e8 9f eb 40 fb 66 45 39 ef 0f 85 d6 02 00 00 e8 b0 ea 40 fb <41> 0f b7 d5 4c 89 f6 48 8d bb c8 00 00 00 e8 fd ee ff ff 31 ff 41
RSP: 0018:ffff88805c877498 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000040000 RBX: ffff88805e198000 RCX: ffffc9000815e000
RDX: 0000000000040000 RSI: ffffffff86319ed0 RDI: 0000000000000002
RBP: ffff88805c877500 R08: ffff888089848080 R09: ffffed1015d06cd4
R10: ffffed1015d06cd3 R11: ffff8880ae83669b R12: dffffc0000000000
R13: 000000000000000a R14: ffff88805c877840 R15: 000000000000000a
 xfrm_lookup_with_ifid+0x1de/0x1fb0 net/xfrm/xfrm_policy.c:3035
 xfrm_lookup net/xfrm/xfrm_policy.c:3172 [inline]
 xfrm_lookup_route+0x3b/0x1f0 net/xfrm/xfrm_policy.c:3183
 ip6_dst_lookup_flow+0x189/0x220 net/ipv6/ip6_output.c:1156
 inet6_csk_route_socket+0x85d/0xe80 net/ipv6/inet6_connection_sock.c:106
 inet6_csk_xmit+0x110/0x5ba net/ipv6/inet6_connection_sock.c:121
 l2tp_xmit_core net/l2tp/l2tp_core.c:1030 [inline]
 l2tp_xmit_skb+0x1112/0x13e0 net/l2tp/l2tp_core.c:1132
 pppol2tp_sendmsg+0x4af/0x6c0 net/l2tp/l2tp_ppp.c:325
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:657
 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2311
 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg net/socket.c:2439 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2439
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd b7 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 b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f83756b4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459829
RDX: 0000000000000004 RSI: 0000000020003f40 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f83756b56d4
R13: 00000000004c700e R14: 00000000004dc648 R15: 00000000ffffffff