rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=ff4c/1/0x4000000000000000 softirq=20227/20227 fqs=0
rcu: 	(detected by 0, t=10506 jiffies, g=15357, q=195 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 7288 Comm: syz.1.403 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:check_preemption_disabled+0x40/0x120
Code: 08 65 8b 05 c6 5e 26 07 65 8b 0d bb 5e 26 07 f7 c1 ff ff ff 7f 74 23 65 48 8b 0d 9b 5e 26 07 48 3b 4c 24 08 0f 85 cc 00 00 00 <48> 83 c4 10 5b 41 5e 41 5f 5d e9 81 ca 02 00 cc 48 c7 04 24 00 00
RSP: 0018:ffffc900001e07e0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000087 RCX: fdf2a6e6dbc49a00
RDX: 0000000000000001 RSI: ffffffff8dba98a1 RDI: ffffffff8be33e80
RBP: ffff88810b068b18 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200003c100 R12: 0000000000000001
R13: 0000000000000001 R14: ffff888136627a98 R15: ffff88810b068000
FS:  00007f57f09696c0(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c39d985 CR3: 000000010a474000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 lock_release+0x27a/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:unwind_next_frame+0x223/0x2390
Code: 86 65 18 00 00 44 89 f8 4c 8d 2c 85 6c 50 e0 90 4c 89 e8 48 c1 e8 03 0f b6 04 28 84 c0 48 89 eb 0f 85 1c 1c 00 00 45 8b 6d 00 <44> 89 f8 ff c0 48 8d 2c 85 6c 50 e0 90 48 89 e8 48 c1 e8 03 0f b6
RSP: 0018:ffffc9000416f9b8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: fdf2a6e6dbc49a00
RDX: 00000000000a7e25 RSI: ffffffff8be33e60 RDI: ffffffff8be33e20
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff8172d195
R10: ffffc9000416fad8 R11: ffffffff81ac4d00 R12: ffffffff8100012f
R13: 0000000000000003 R14: ffffc9000416fa88 R15: 0000000000000001
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 ref_tracker_free+0xef/0x7d0
 __sk_destruct+0x3c3/0x660
 tun_chr_close+0x17b/0x1c0
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f57efb8eba9
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:00007f57f0969038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffea RBX: 00007f57efdd5fa0 RCX: 00007f57efb8eba9
RDX: 0000000000006040 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f57efc11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f57efdd6038 R14: 00007f57efdd5fa0 R15: 00007ffd59f03648
 </TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g15357 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:R  running task     stack:26728 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>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 7279 Comm: syz.2.401 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:smp_call_function_many_cond+0xd33/0x12d0
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b6 63 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 5f 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 45 5f
RSP: 0018:ffffc9000335f340 EFLAGS: 00000293
RAX: ffffffff81b4621b RBX: 1ffff11026cc7f61 RCX: ffff88803a84b980
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000335f4c0 R08: ffffffff8fa3a937 R09: 1ffffffff1f47526
R10: dffffc0000000000 R11: fffffbfff1f47527 R12: ffff88813663fb08
R13: dffffc0000000000 R14: ffff88804b03b1c0 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000004 CR3: 000000000df36000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80
 flush_tlb_mm_range+0x6b1/0x12d0
 tlb_flush_mmu+0x1a7/0x680
 tlb_finish_mmu+0xc3/0x1d0
 free_ldt_pgtables+0x17b/0x320
 exit_mmap+0x17c/0xb50
 __mmput+0x118/0x430
 exit_mm+0x1da/0x2c0
 do_exit+0x648/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe3e498eba9
Code: Unable to access opcode bytes at 0x7fe3e498eb7f.
RSP: 002b:00007fe3e57b3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffed RBX: 00007fe3e4bd6090 RCX: 00007fe3e498eba9
RDX: 0000200000000080 RSI: 00000000000089f3 RDI: 0000000000000006
RBP: 00007fe3e4a11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe3e4bd6128 R14: 00007fe3e4bd6090 R15: 00007ffe4fc3edf8
 </TASK>
