rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8223/1:b..l
	(detected by 0, t=10502 jiffies, g=482245, q=19)
task:kworker/u4:6    state:R  running task     stack:24192 pid: 8223 ppid:     2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 context_switch kernel/sched/core.c:4940 [inline]
 __schedule+0xb44/0x5960 kernel/sched/core.c:6287
 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6687
 irqentry_exit+0x31/0x80 kernel/entry/common.c:425
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5593
Code: ba a5 7e 83 f8 01 0f 85 b4 02 00 00 9c 58 f6 c4 02 0f 85 9f 02 00 00 48 83 7c 24 08 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc900048f7a58 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 1ffff9200091ef4d RCX: 0bfb665856c30ac9
RDX: 1ffff1100393dbf3 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8fd0c9e7
R10: fffffbfff1fa193c R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: ffffffff8b981ee0 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:267 [inline]
 rcu_read_lock include/linux/rcupdate.h:687 [inline]
 inet_twsk_purge+0x117/0x7d0 net/ipv4/inet_timewait_sock.c:268
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:171
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:593
 process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g482245 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=135962
rcu: rcu_preempt kthread starved for 10502 jiffies! g482245 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:28696 pid:   14 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:4940 [inline]
 __schedule+0xb44/0x5960 kernel/sched/core.c:6287
 schedule+0xd3/0x270 kernel/sched/core.c:6366
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881
 rcu_gp_fqs_loop+0x186/0x800 kernel/rcu/tree.c:1957
 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2130
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
----------------
Code disassembly (best guess):
   0:	ba a5 7e 83 f8       	mov    $0xf8837ea5,%edx
   5:	01 0f                	add    %ecx,(%rdi)
   7:	85 b4 02 00 00 9c 58 	test   %esi,0x589c0000(%rdx,%rax,1)
   e:	f6 c4 02             	test   $0x2,%ah
  11:	0f 85 9f 02 00 00    	jne    0x2b6
  17:	48 83 7c 24 08 00    	cmpq   $0x0,0x8(%rsp)
  1d:	74 01                	je     0x20
  1f:	fb                   	sti
  20:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  27:	fc ff df
* 2a:	48 01 c3             	add    %rax,%rbx <-- trapping instruction
  2d:	48 c7 03 00 00 00 00 	movq   $0x0,(%rbx)
  34:	48 c7 43 08 00 00 00 	movq   $0x0,0x8(%rbx)
  3b:	00
  3c:	48                   	rex.W
  3d:	8b                   	.byte 0x8b
  3e:	84                   	.byte 0x84
  3f:	24                   	.byte 0x24