rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 ticks this GP) idle=b66/1/0x4000000000000002 softirq=202092/202092 fqs=0 
	(t=11220 jiffies g=260737 q=203)
rcu: rcu_preempt kthread starved for 11220 jiffies! g260737 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29392    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x755/0x15b0 kernel/sched/core.c:3921
 schedule+0xa8/0x270 kernel/sched/core.c:3985
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1893
 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 1
CPU: 1 PID: 3909 Comm: kworker/1:1 Not tainted 5.3.0-rc2-next-20190801 #57
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+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:1724
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1299
 __run_hrtimer kernel/time/hrtimer.c:1493 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1555
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1617
 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:828
 </IRQ>
RIP: 0010:preempt_schedule_irq+0xab/0x160 kernel/sched/core.c:4169
Code: 00 00 e8 08 80 0f fa e8 d3 01 39 fa 4c 89 f0 48 c1 e8 03 80 3c 18 00 75 7d 48 83 3d be 51 94 01 00 74 6f fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 cb db ff ff 48 c7 c0 a8 f4 d2 88 48 c1 e8 03 80
RSP: 0018:ffff888063f47ad8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11a5e96 RBX: dffffc0000000000 RCX: 1ffffffff134c0be
RDX: 0000000000000000 RSI: ffffffff8177a50e RDI: ffffffff873ea2dd
RBP: ffff888063f47af8 R08: ffff88808bc6a200 R09: ffffed1015d26af5
R10: ffffed1015d26af4 R11: ffff8880ae9357a3 R12: ffffed101178d440
R13: ffff88808bc6a200 R14: ffffffff88d2f4b0 R15: 0000000000000000
 retint_kernel+0x1b/0x2b
RIP: 0010:delay_tsc+0x72/0xc0 arch/x86/lib/delay.c:66
Code: 01 f9 66 90 48 c1 e2 20 48 89 d3 48 09 c3 48 89 d8 4c 29 e0 4c 39 f0 73 24 bf 01 00 00 00 e8 75 bb 10 fa 65 8b 05 16 ad c4 78 <85> c0 75 bb e8 b5 15 c3 f9 eb b4 49 29 dc 4d 01 e6 eb 93 bf 01 00
RSP: 0018:ffff888063f47bb0 EFLAGS: 00000297 ORIG_RAX: ffffffffffffff02
RAX: 0000000080000000 RBX: 0000032cae7c1983 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff833e0d1c RDI: 0000000000000001
RBP: ffff888063f47bd0 R08: ffff88808bc6a200 R09: 0000000000000040
R10: 0000000000000040 R11: ffffffff88e54287 R12: 0000032cae7c0d11
R13: 0000000000000001 R14: 0000000000002ced R15: 000000000000157d
 __delay arch/x86/lib/delay.c:161 [inline]
 __const_udelay+0x59/0x80 arch/x86/lib/delay.c:175
 try_check_zero+0x201/0x330 kernel/rcu/srcutree.c:705
 srcu_advance_state kernel/rcu/srcutree.c:1142 [inline]
 process_srcu+0x329/0xe20 kernel/rcu/srcutree.c:1237
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352