rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=d0a/1/0x4000000000000002 softirq=12111/12112 fqs=19 
	(t=10501 jiffies g=10641 q=338)
rcu: rcu_preempt kthread starved for 10461 jiffies! g10641 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29240    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1670 [inline]
 rcu_gp_kthread+0xa10/0x1b40 kernel/rcu/tree.c:1837
 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: 9464 Comm: syz-executor.0 Not tainted 5.5.0-rc6-next-20200116-syzkaller #0
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+0x197/0x210 lib/dump_stack.c:118
 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+0x1a2/0x1ef kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
 rcu_pending kernel/rcu/tree.c:3097 [inline]
 rcu_sched_clock_irq.cold+0x570/0xcc6 kernel/rcu/tree.c:2297
 update_process_times+0x2d/0x70 kernel/time/timer.c:1726
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x4f/0x80 kernel/locking/spinlock.c:199
Code: c0 88 ba b3 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 33 48 83 3d 52 b2 c5 01 00 74 20 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 67 d8 62 f9 65 8b 05 38 16 14 78 85 c0 74 06 41
RSP: 0000:ffffc90005857ca0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff1367751 RBX: 0000000000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff888051bb49dc
RBP: ffffc90005857ca8 R08: ffff888051bb4140 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880518fd2c0
R13: ffff8880518fd400 R14: dffffc0000000000 R15: 000000000000000b
 spin_unlock_irq include/linux/spinlock.h:388 [inline]
 get_signal+0x1bee/0x24f0 kernel/signal.c:2737
 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x321/0x3a0 arch/x86/entry/common.c:195
 ret_from_intr+0x26/0x36
RIP: 0033:0x405899
Code: d0 ff ff ff 01 48 8b 7c 24 28 c7 44 24 34 00 00 00 00 e8 1a dd 01 00 85 c0 75 23 48 6b 44 24 20 18 8b 7c 24 1c 48 03 44 24 38 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 b7 f8 00 00 89 44 24 34 64 f0
RSP: 002b:00007f0c1bc31a70 EFLAGS: 00010202
RAX: 00000000267b3340 RBX: 00007f0c1bc326d4 RCX: 0000000000415197
RDX: 4e65a5d3a681be36 RSI: 0000000000000000 RDI: 000000000000000a
RBP: 000000000075bf20 R08: 00007f0c1bc31a70 R09: 000000000075bf20
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000ba7 R14: 00000000004cc802 R15: 000000000075bf2c