rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=526/1/0x4000000000000004 softirq=71907/71911 fqs=0 
	(t=29983 jiffies g=77989 q=284)
rcu: rcu_preempt kthread starved for 29983 jiffies! g77989 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29264    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3380 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4080
 schedule+0xdc/0x2b0 kernel/sched/core.c:4154
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline]
 rcu_gp_kthread+0xa10/0x1940 kernel/rcu/tree.c:1818
 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: 9319 Comm: syz-executor.0 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+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+0x183/0x1cf 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+0x51a/0xc37 kernel/rcu/tree.c:2276
 update_process_times+0x2d/0x70 kernel/time/timer.c:1726
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:171
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1314
 __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:1119 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
RIP: 0010:ffs arch/x86/include/asm/bitops.h:297 [inline]
RIP: 0010:__do_softirq+0x227/0x98c kernel/softirq.c:280
Code: c7 c0 c8 b1 b3 89 48 c1 e8 03 42 80 3c 30 00 0f 85 b1 06 00 00 48 83 3d ae af 93 01 00 0f 84 d6 05 00 00 fb 66 0f 1f 44 00 00 <b8> ff ff ff ff 48 c7 45 c8 00 91 a0 89 0f bc 45 d4 83 c0 01 89 45
RSP: 0018:ffffc90000da8f20 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff1367639 RBX: ffff8880478b0340 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffff8880478b0c00 RDI: ffff8880478b0bd4
RBP: ffffc90000da8fa0 R08: 1ffffffff16a3396 R09: fffffbfff16a3397
R10: fffffbfff16a3396 R11: ffffffff8b519cb7 R12: 0000000000000025
R13: 0000000000000025 R14: dffffc0000000000 R15: 0000000000000000
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 do_IRQ+0xe3/0x280 arch/x86/kernel/irq.c:263
 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:607
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:lock_acquire+0x20b/0x410 kernel/locking/lockdep.c:4487
Code: 94 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 d3 01 00 00 48 83 3d b9 71 58 08 00 0f 84 53 01 00 00 48 8b 7d c8 57 9d <0f> 1f 44 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b
RSP: 0018:ffffc90017457c60 EFLAGS: 00000282 ORIG_RAX: ffffffffffffffda
RAX: 1ffffffff1367637 RBX: ffff8880478b0340 RCX: ffffffff815ae510
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: 0000000000000282
RBP: ffffc90017457ca8 R08: 1ffffffff16a3391 R09: fffffbfff16a3392
R10: ffff8880478b0c00 R11: ffff8880478b0340 R12: ffffc900174b2e20
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000002
 rcu_lock_acquire include/linux/rcupdate.h:208 [inline]
 srcu_read_lock include/linux/srcu.h:155 [inline]
 vcpu_run arch/x86/kvm/x86.c:8542 [inline]
 kvm_arch_vcpu_ioctl_run+0x678/0x17b0 arch/x86/kvm/x86.c:8733
 kvm_vcpu_ioctl+0x4dc/0xfc0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2932
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x123/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c479
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc678e66c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc678e676d4 RCX: 000000000045c479
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000008
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003bf R14: 00000000004c6098 R15: 000000000076bf2c