rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=483c/1/0x4000000000000000 softirq=26524/26524 fqs=0
rcu: 	(detected by 0, t=10505 jiffies, g=20225, q=309 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 8611 Comm: syz.2.789 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:rcu_is_watching+0x9/0xb0
Code: 59 03 eb cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 <65> ff 05 30 5e fa 10 e8 1b 0f d4 09 89 c3 83 f8 08 73 65 49 bf 00
RSP: 0018:ffffc900001e07f8 EFLAGS: 00000097
RAX: 0000000000000001 RBX: 0000000000000802 RCX: ffff88811a680000
RDX: 0000000000010000 RSI: ffffffff81ada91e RDI: ffff888136627a98
RBP: ffffc900001e0918 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200003c100 R12: dffffc0000000000
R13: ffffffff81ada91e R14: ffff888136627a98 R15: 1ffff9200003c110
FS:  00007f7fccbba6c0(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f34595b6940 CR3: 0000000110e46000 CR4: 00000000000006f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_release+0x4b/0x3e0
 _raw_spin_unlock_irqrestore+0x70/0x110
 hrtimer_try_to_cancel+0x3be/0x420
 hrtimer_cancel+0x3b/0x50
 cpu_clock_event_stop+0xd9/0x130
 __perf_event_overflow+0x580/0xe40
 perf_swevent_hrtimer+0x3c5/0x550
 __hrtimer_run_queues+0x4e0/0xc60
 hrtimer_interrupt+0x45b/0xaa0
 __sysvec_apic_timer_interrupt+0x10b/0x410
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:tun_chr_close+0x15d/0x1c0
Code: 39 f8 44 fb e8 d4 7e ee 02 4c 8d b3 80 00 00 00 4c 89 f7 be 04 00 00 00 e8 90 7d a8 fb bd ff ff ff ff f0 0f c1 ab 80 00 00 00 <bf> 01 00 00 00 89 ee e8 47 fc 44 fb 83 fd 01 75 0f e8 fd f7 44 fb
RSP: 0018:ffffc90008247d48 EFLAGS: 00000257
RAX: 143f524918ff6f01 RBX: ffff88811fb62000 RCX: ffffffff867ac940
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88811fb62080
RBP: 0000000000000001 R08: ffff88811fb62083 R09: 1ffff11023f6c410
R10: dffffc0000000000 R11: ffffed1023f6c411 R12: 1ffff110042025c9
R13: ffffffff867ac7f0 R14: ffff88811fb62080 R15: dffffc0000000000
 __fput+0x44c/0xa70
 fput_close_sync+0x119/0x200
 __x64_sys_close+0x7f/0x110
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7fcbd8eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7fccbba038 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f7fcbfd5fa0 RCX: 00007f7fcbd8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000b
RBP: 00007f7fcbe11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7fcbfd6038 R14: 00007f7fcbfd5fa0 R15: 00007ffccb54e9f8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10504 jiffies! g20225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=7020
rcu: rcu_preempt kthread starved for 10505 jiffies! g20225 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27160 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
