rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10494 ticks this GP) idle=306/1/0x4000000000000002 softirq=13391/13391 fqs=1160 
	(t=10500 jiffies g=8673 q=172)
NMI backtrace for cpu 0
CPU: 0 PID: 8900 Comm: syz-executor.4 Not tainted 5.6.0-rc4-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+0x1e9/0x30e lib/dump_stack.c:118
 nmi_cpu_backtrace+0x9f/0x180 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x169/0x250 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+0x171f/0x1970 kernel/rcu/tree.c:2276
 update_process_times+0x12c/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:171 [inline]
 tick_sched_timer+0x254/0x410 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x3cf/0x7d0 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x373/0xd60 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/paravirt.h:764 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/paravirt.h:777 [inline]
RIP: 0010:__local_bh_disable_ip+0x84/0x150 kernel/softirq.c:116
Code: 00 49 89 c7 48 c7 c0 60 d4 0a 89 48 c1 e8 03 42 80 3c 20 00 74 0c 48 c7 c7 60 d4 0a 89 e8 64 23 68 00 48 83 3d fc 0c c2 07 00 <0f> 84 bd 00 00 00 fa 66 0f 1f 44 00 00 65 01 1d 54 56 b9 7e 65 8b
RSP: 0018:ffffc900027e76f8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff1215a8c RBX: 0000000000000200 RCX: ffff888095d6c040
RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff868a1455
RBP: ffff888099576460 R08: dffffc0000000000 R09: fffffbfff15db918
R10: fffffbfff15db918 R11: 0000000000000000 R12: dffffc0000000000
R13: 000000000000ec8d R14: ffffffff868a1455 R15: 0000000000000282
 get_next_corpse net/netfilter/nf_conntrack_core.c:2136 [inline]
 nf_ct_iterate_cleanup+0xa0/0x3a0 net/netfilter/nf_conntrack_core.c:2171
 nf_ct_iterate_cleanup_net+0xfc/0x150 net/netfilter/nf_conntrack_core.c:2256
 masq_device_event+0x9b/0xd0 net/netfilter/nf_nat_masquerade.c:88
 notifier_call_chain kernel/notifier.c:83 [inline]
 __raw_notifier_call_chain kernel/notifier.c:361 [inline]
 raw_notifier_call_chain+0xd4/0x170 kernel/notifier.c:368
 call_netdevice_notifiers_info net/core/dev.c:1948 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1960 [inline]
 call_netdevice_notifiers net/core/dev.c:1974 [inline]
 dev_close_many+0x38e/0x530 net/core/dev.c:1549
 rollback_registered_many+0x44d/0x1450 net/core/dev.c:8787
 rollback_registered net/core/dev.c:8855 [inline]
 unregister_netdevice_queue+0x2bb/0x470 net/core/dev.c:9947
 unregister_netdevice include/linux/netdevice.h:2715 [inline]
 __tun_detach+0x11c4/0x1bc0 drivers/net/tun.c:723
 tun_detach drivers/net/tun.c:740 [inline]
 tun_chr_close+0xed/0x130 drivers/net/tun.c:3459
 __fput+0x2d8/0x730 fs/file_table.c:280
 task_work_run+0x176/0x1b0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x5ef/0x1f80 kernel/exit.c:801
 do_group_exit+0x15e/0x2c0 kernel/exit.c:899
 get_signal+0x13cf/0x1d60 kernel/signal.c:2739
 do_signal+0x33/0x610 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop arch/x86/entry/common.c:160 [inline]
 prepare_exit_to_usermode+0x32a/0x600 arch/x86/entry/common.c:195
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c4a9
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:00007fbeab9c2cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 000000000076bf28 RCX: 000000000045c4a9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000076bf28
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000076bf2c
R13: 00007ffc2c90641f R14: 00007fbeab9c39c0 R15: 000000000076bf2c