rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10539 ticks this GP) idle=13a/1/0x4000000000000002 softirq=271622/271630 fqs=47 
	(t=10500 jiffies g=323501 q=120)
rcu: rcu_preempt kthread starved for 10296 jiffies! g323501 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29384    10      2 0x80004000
Call Trace:
 schedule+0xd0/0x2a0 kernel/sched/core.c:4154
 schedule_timeout+0x474/0xba0 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline]
 rcu_gp_kthread+0x9d9/0x17d0 kernel/rcu/tree.c:1818
 kthread+0x357/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 21043 Comm: syz-executor.1 Not tainted 5.6.0-rc3-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+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x169/0x1b3 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:3030 [inline]
 rcu_sched_clock_irq.cold+0x518/0xc55 kernel/rcu/tree.c:2276
 update_process_times+0x25/0x60 kernel/time/timer.c:1726
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:171
 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x32c/0xdd0 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1144
 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+0x4b/0x80 kernel/locking/spinlock.c:199
Code: c0 88 b2 73 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 31 48 83 3d 66 5f b6 01 00 74 25 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 6b 5e 91 f9 65 8b 05 4c cb 44 78 85 c0 74 02 5d
RSP: 0000:ffffc90001737ce0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff12e7651 RBX: ffff88807c8cd680 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a7ffa894
RBP: ffff88807c8cd540 R08: ffff8880a7ffa000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: dffffc0000000000 R14: 000000000000000b R15: ffff88807c8cd540
 spin_unlock_irq include/linux/spinlock.h:388 [inline]
 get_signal+0x1bce/0x24e0 kernel/signal.c:2742
 do_signal+0x7e/0x13f0 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x305/0x380 arch/x86/entry/common.c:195
 ret_from_intr+0x26/0x36
RIP: 0033:0x4044f9
Code: d0 ff ff ff 01 48 8b 7c 24 20 c7 44 24 2c 00 00 00 00 e8 ca 01 02 00 85 c0 75 23 48 6b 44 24 18 18 8b 7c 24 28 48 03 44 24 30 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 67 1d 01 00 89 44 24 2c 64 f0
RSP: 002b:00007f566adc89e0 EFLAGS: 00010206
RAX: 00000000216a7118 RBX: 00007f566adc96d4 RCX: 00000000004162a7
RDX: 0d14ce957222b6a5 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000076bfc0 R08: 00007f566adc89e0 R09: 000000000076bfc0
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000c1c R14: 00000000004c13cb R15: 000000000076bfcc