rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10495 ticks this GP) idle=f8e/1/0x4000000000000002 softirq=13767/13767 fqs=5242 
rcu: 	 (t=10500 jiffies g=11973 q=1037)
NMI backtrace for cpu 0
CPU: 0 PID: 2987 Comm: kworker/0:2 Not tainted 5.1.0-rc2+ #117
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient gc_worker
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1be/0x236 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.c:1223
 print_cpu_stall kernel/rcu/tree.c:1360 [inline]
 check_cpu_stall kernel/rcu/tree.c:1434 [inline]
 rcu_pending kernel/rcu/tree.c:3103 [inline]
 rcu_sched_clock_irq.cold+0x500/0xa4a kernel/rcu/tree.c:2544
 update_process_times+0x32/0x80 kernel/time/timer.c:1635
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:161
 tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1271
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x33e/0xde0 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline]
 smp_apic_timer_interrupt+0x120/0x570 arch/x86/kernel/apic/apic.c:1060
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:cpu_relax arch/x86/include/asm/processor.h:666 [inline]
RIP: 0010:virt_spin_lock arch/x86/include/asm/qspinlock.h:84 [inline]
RIP: 0010:native_queued_spin_lock_slowpath+0x132/0x9f0 kernel/locking/qspinlock.c:334
Code: 00 00 00 48 8b 45 d0 65 48 33 04 25 28 00 00 00 0f 85 37 07 00 00 48 81 c4 98 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 f3 90 <e9> 73 ff ff ff 8b 45 98 4c 8d 65 d8 3d 00 01 00 00 0f 84 e5 00 00
RSP: 0018:ffff88809ef9f948 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: ffffe8ffffc6b210 RCX: ffffffff81581bb7
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffe8ffffc6b210
RBP: ffff88809ef9fa08 R08: 1ffffd1ffff8d642 R09: fffff91ffff8d643
R10: fffff91ffff8d642 R11: ffffe8ffffc6b213 R12: 0000000000000001
R13: 0000000000000003 R14: fffff91ffff8d642 R15: 000000000000000b
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:654 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:50 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:90 [inline]
 do_raw_spin_lock+0x20e/0x2e0 kernel/locking/spinlock_debug.c:113
 __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_lock+0x37/0x40 kernel/locking/spinlock.c:144
 spin_lock include/linux/spinlock.h:329 [inline]
 nf_ct_add_to_dying_list+0xdb/0x210 net/netfilter/nf_conntrack_core.c:472
 nf_ct_delete_from_lists+0x3c1/0x530 net/netfilter/nf_conntrack_core.c:619
 nf_ct_delete net/netfilter/nf_conntrack_core.c:646 [inline]
 nf_ct_delete+0x1d0/0x4c0 net/netfilter/nf_conntrack_core.c:624
 nf_ct_kill include/net/netfilter/nf_conntrack.h:219 [inline]
 nf_ct_gc_expired net/netfilter/nf_conntrack_core.c:688 [inline]
 nf_ct_gc_expired+0x2da/0x350 net/netfilter/nf_conntrack_core.c:682
 gc_worker+0xb2a/0xea0 net/netfilter/nf_conntrack_core.c:1234
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x357/0x430 kernel/kthread.c:253
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352