INFO: rcu_sched self-detected stall on CPU
	1-...!: (124993 ticks this GP) idle=d4a/1/4611686018427387906 softirq=47579/47579 fqs=42 
	 (t=125000 jiffies g=25763 c=25762 q=565)
rcu_sched kthread starved for 124819 jiffies! g25763 c25762 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1
rcu_sched       R  running task    22720     8      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2798 [inline]
 __schedule+0x8eb/0x2060 kernel/sched/core.c:3374
 schedule+0xf5/0x430 kernel/sched/core.c:3433
 schedule_timeout+0x15f/0x270 kernel/time/timer.c:1755
 rcu_gp_kthread+0x9e5/0x1930 kernel/rcu/tree.c:2232
 kthread+0x38b/0x470 kernel/kthread.c:242
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
NMI backtrace for cpu 1
CPU: 1 PID: 14830 Comm: syz-executor6 Not tainted 4.14.0-rc5-mm1+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 nmi_cpu_backtrace+0x20e/0x240 lib/nmi_backtrace.c:102
 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:61
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 trigger_single_cpu_backtrace include/linux/nmi.h:155 [inline]
 rcu_dump_cpu_stacks+0x186/0x1da kernel/rcu/tree.c:1377
 print_cpu_stall kernel/rcu/tree.c:1526 [inline]
 check_cpu_stall.isra.65+0xbb8/0x15b0 kernel/rcu/tree.c:1594
 __rcu_pending kernel/rcu/tree.c:3358 [inline]
 rcu_pending kernel/rcu/tree.c:3420 [inline]
 rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2760
 update_process_times+0x30/0x60 kernel/time/timer.c:1590
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1192
 __run_hrtimer kernel/time/hrtimer.c:1213 [inline]
 __hrtimer_run_queues+0x349/0xe10 kernel/time/hrtimer.c:1277
 hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1311
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:770
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:777 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x5e/0xba kernel/locking/spinlock.c:189
RSP: 0018:ffff8801d4827558 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff11
RAX: dffffc0000000000 RBX: 0000000000000282 RCX: 0000000000000000
RDX: 1ffffffff0b58f39 RSI: 0000000000000001 RDI: 0000000000000282
RBP: ffff8801d4827568 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9ebad80
R13: ffff8801c65fc080 R14: 0000000000000001 R15: ffff8801c9ebadb8
 spin_unlock_irqrestore include/linux/spinlock.h:369 [inline]
 prepare_to_wait+0x192/0x4d0 kernel/sched/wait.c:238
 sock_wait_for_wmem net/core/sock.c:2030 [inline]
 sock_alloc_send_pskb+0x4c5/0x9b0 net/core/sock.c:2076
 tun_alloc_skb drivers/net/tun.c:1349 [inline]
 tun_get_user+0x91a/0x36d0 drivers/net/tun.c:1636
 tun_chr_write_iter+0xb9/0x160 drivers/net/tun.c:1792
 call_write_iter include/linux/fs.h:1770 [inline]
 new_sync_write fs/read_write.c:468 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:481
 vfs_write+0x189/0x510 fs/read_write.c:543
 SYSC_write fs/read_write.c:588 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:580
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x452719
RSP: 002b:00007f04befa3be8 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452719
RDX: 0000000000001026 RSI: 00000000209ed000 RDI: 0000000000000015
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f3500
R13: 00000000ffffffff R14: 00007f04befa46d4 R15: 0000000000000000