rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10500 ticks this GP) idle=952/1/0x4000000000000002 softirq=65599/65599 fqs=0 
rcu: 	 (t=10500 jiffies g=93785 q=1780)
rcu: rcu_preempt kthread starved for 10500 jiffies! g93785 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I22696    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2831 [inline]
 __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472
 schedule+0xfe/0x460 kernel/sched/core.c:3516
 schedule_timeout+0x140/0x260 kernel/time/timer.c:1804
 rcu_gp_fqs_loop+0x762/0xa80 kernel/rcu/tree.c:1934
 rcu_gp_kthread+0x341/0xc70 kernel/rcu/tree.c:2090
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350
NMI backtrace for cpu 0
CPU: 0 PID: 27095 Comm: syz-executor3 Not tainted 4.19.0+ #91
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+0x244/0x39d lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.1+0x5c/0xa1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed 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:162 [inline]
 rcu_dump_cpu_stacks+0x16f/0x1bc kernel/rcu/tree.c:1195
 print_cpu_stall.cold.67+0x1f3/0x3c7 kernel/rcu/tree.c:1334
 check_cpu_stall kernel/rcu/tree.c:1408 [inline]
 rcu_pending kernel/rcu/tree.c:2961 [inline]
 rcu_check_callbacks+0xf3b/0x13f0 kernel/rcu/tree.c:2506
 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+0x41c/0x10d0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x313/0x780 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1034 [inline]
 smp_apic_timer_interrupt+0x1a1/0x760 arch/x86/kernel/apic/apic.c:1059
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:801
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x4c/0x50 kernel/kcov.c:111
Code: d8 12 00 00 83 fa 02 75 20 48 8b 88 e0 12 00 00 8b 80 dc 12 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 5d <c3> 0f 1f 00 55 40 0f b6 d6 40 0f b6 f7 31 ff 48 89 e5 48 8b 4d 08
RSP: 0018:ffff8801d1ecef18 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc9000c73d000
RDX: 0000000000040000 RSI: ffffffff86bf861e RDI: 0000000000000001
RBP: ffff8801d1ecefe8 R08: ffff8801c37a0080 R09: ffffed0037cbc92c
R10: ffffed0037cbc92c R11: ffff8801be5e4963 R12: dffffc0000000000
R13: ffffed003a3d9df0 R14: 0000000000000000 R15: ffff8801d1ecf6a0
 xfrm_lookup_with_ifid+0x2a1/0x2b80 net/xfrm/xfrm_policy.c:2063
 xfrm_lookup net/xfrm/xfrm_policy.c:2200 [inline]
 xfrm_lookup_route+0x3c/0x1f0 net/xfrm/xfrm_policy.c:2211
 ip6_dst_lookup_flow+0x1c6/0x270 net/ipv6/ip6_output.c:1083
 inet6_csk_route_socket+0x8bd/0x1020 net/ipv6/inet6_connection_sock.c:110
 inet6_csk_xmit+0x118/0x630 net/ipv6/inet6_connection_sock.c:125
 l2tp_xmit_core net/l2tp/l2tp_core.c:1030 [inline]
 l2tp_xmit_skb+0x134c/0x1670 net/l2tp/l2tp_core.c:1132
 pppol2tp_sendmsg+0x4b1/0x6c0 net/l2tp/l2tp_ppp.c:329
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x51d/0x930 net/socket.c:2116
 __sys_sendmmsg+0x246/0x6d0 net/socket.c:2211
 __do_sys_sendmmsg net/socket.c:2240 [inline]
 __se_sys_sendmmsg net/socket.c:2237 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2237
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
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:00007fb9c4329c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457569
RDX: 0800000000000059 RSI: 0000000020005fc0 RDI: 0000000000000006
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb9c432a6d4
R13: 00000000004c374a R14: 00000000004d57b8 R15: 00000000ffffffff