EXT4-fs warning (device sda1): verify_group_input:104: Cannot add at group 21 (only 16 groups)
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 	0-....: (105000 ticks this GP) idle=036/1/0x4000000000000002 softirq=19866/19866 fqs=26227 
rcu: 	 (t=105010 jiffies g=33229 q=1528)
NMI backtrace for cpu 0
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 4.18.0-rc7-next-20180803+ #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events rtc_timer_do_work
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x151/0x192 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:162 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1340
 print_cpu_stall.cold.78+0x2fb/0x59c kernel/rcu/tree.c:1478
 check_cpu_stall kernel/rcu/tree.c:1550 [inline]
 __rcu_pending kernel/rcu/tree.c:3276 [inline]
 rcu_pending kernel/rcu/tree.c:3319 [inline]
 rcu_check_callbacks+0xd93/0x1660 kernel/rcu/tree.c:2665
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x3eb/0x10c0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x2f3/0x750 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1028 [inline]
 smp_apic_timer_interrupt+0x165/0x730 arch/x86/kernel/apic/apic.c:1053
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:867
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa1/0xc0 kernel/locking/spinlock.c:184
Code: e8 b0 f1 87 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 21 48 83 3d be 3c 39 01 00 74 0e 48 89 df 57 9d <0f> 1f 44 00 00 eb bb 0f 0b 0f 0b e8 bf 25 03 fb eb 97 e8 b8 25 03
RSP: 0018:ffff8801d9eb7320 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 0000000000000286 RCX: ffffffff81606487
RDX: 1ffffffff0fe361d RSI: 0000000000000004 RDI: 0000000000000286
RBP: ffff8801d9eb7330 R08: ffffed0039c870eb R09: ffffed0039c870ea
R10: ffffed0039c870ea R11: ffff8801ce438753 R12: ffff8801ce438750
R13: 0000000000000090 R14: ffff8801ce438750 R15: dffffc0000000000
 spin_unlock_irqrestore include/linux/spinlock.h:384 [inline]
 rtc_handle_legacy_irq+0x76/0xd0 drivers/rtc/interface.c:608
 rtc_uie_update_irq+0x1f/0x30 drivers/rtc/interface.c:637
 rtc_timer_do_work+0x287/0x11d0 drivers/rtc/interface.c:918
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x35a/0x420 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-... } 105533 jiffies s: 453 root: 0x1/.
rcu: blocking rcu_node structures:
Task dump for CPU 0:
kworker/0:0     R  running task    20656     5      2 0x80000008
Workqueue: events rtc_timer_do_work
Call Trace: