INFO: rcu_sched detected stalls on CPUs/tasks:
	(detected by 1, t=120002 jiffies, g=21025, c=21024, q=263)
All QSes seen, last rcu_sched kthread activity 120002 (4294923563-4294803561), jiffies_till_next_fqs=3, root ->qsmask 0x0
kworker/u4:0    R  running task    56128     6      2 0x80000008
Workqueue: netns cleanup_net
Call Trace:
 <IRQ>
 sched_show_task+0x610/0x740 kernel/sched/core.c:5346
 print_other_cpu_stall kernel/rcu/tree.c:1481 [inline]
 check_cpu_stall kernel/rcu/tree.c:1599 [inline]
 __rcu_pending kernel/rcu/tree.c:3356 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x277a/0x2ae0 kernel/rcu/tree.c:2763
 update_process_times+0x132/0x1a0 kernel/time/timer.c:1636
 tick_sched_handle kernel/time/tick-sched.c:164 [inline]
 tick_sched_timer+0x3ba/0x520 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0xc54/0x1630 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x451/0x13c0 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt+0x6b/0x250 arch/x86/kernel/apic/apic.c:1025
 smp_apic_timer_interrupt+0x5a/0x90 arch/x86/kernel/apic/apic.c:1053
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
RIP: 0010:rep_nop arch/x86/include/asm/processor.h:667 [inline]
RIP: 0010:cpu_relax arch/x86/include/asm/processor.h:672 [inline]
RIP: 0010:csd_lock_wait kernel/smp.c:108 [inline]
RIP: 0010:smp_call_function_single+0x357/0x4e0 kernel/smp.c:302
RSP: 0018:ffff8801d8d1fa40 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81539215 RBX: 0000000000000001 RCX: ffff8801d8c99d40
RDX: 0000000000000000 RSI: aaaaaaaaaaaab000 RDI: ffffea0000000000
RBP: ffff8801d8d1fb10 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81174e40 R12: ffff8801d8d1fab8
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8801d8c9a618
 _rcu_barrier+0x497/0x760 kernel/rcu/tree.c:3544
 rcu_barrier_sched kernel/rcu/tree.c:3584 [inline]
 rcu_barrier+0x1c/0x20 kernel/rcu/tree_plugin.h:898
 cleanup_net+0x10ff/0x16b0 net/core/net_namespace.c:534
 process_one_work+0x12e4/0x1fa0 kernel/workqueue.c:2145
 worker_thread+0x113c/0x24f0 kernel/workqueue.c:2279
 kthread+0x4db/0x6c0 kernel/kthread.c:241
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412
rcu_sched kthread starved for 120002 jiffies! g21025 c21024 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
RCU grace-period kthread stack dump:
rcu_sched       R  running task    61144     9      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2880 [inline]
 __schedule+0x651/0x770 kernel/sched/core.c:3524
 schedule+0x1cc/0x2f0 kernel/sched/core.c:3568
 schedule_timeout+0x3ef/0x580 kernel/time/timer.c:1801
 rcu_gp_kthread+0x21e1/0x38d0 kernel/rcu/tree.c:2231
 kthread+0x4db/0x6c0 kernel/kthread.c:241
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412