rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=552/1/0x4000000000000002 softirq=79129/79132 fqs=0 
rcu: 	 (t=11165 jiffies g=109121 q=162)
NMI backtrace for cpu 1
CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 5.1.0-rc1 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: rcu_gp process_srcu
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:in_lock_functions+0x2/0x20 kernel/locking/spinlock.c:390
Code: 50 00 e9 3e ff ff ff 48 c7 c7 40 54 a6 89 e8 05 69 50 00 eb 88 0f 1f 00 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 31 c0 <48> 81 ff d8 41 0f 87 72 0c 31 c0 48 81 ff 0d 51 0f 87 0f 92 c0 c3
RSP: 0018:ffff8880a980fb88 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: ffffffff870ccc38 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000014f8c RDI: ffffffff870ccc38
RBP: ffff8880a980fba0 R08: ffff8880aa3fa5c0 R09: 0000000000000040
R10: 0000000000000040 R11: ffffffff88a44327 R12: 0000000000000001
R13: 0000000000000007 R14: 0000000000002ced R15: 00000000000004b5
 delay_tsc+0x18/0xc0 arch/x86/lib/delay.c:57
 __delay arch/x86/lib/delay.c:161 [inline]
 __const_udelay+0x5f/0x80 arch/x86/lib/delay.c:175
 try_check_zero+0x201/0x330 kernel/rcu/srcutree.c:709
 srcu_advance_state kernel/rcu/srcutree.c:1146 [inline]
 process_srcu+0x329/0xe20 kernel/rcu/srcutree.c:1241
 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