rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4273/1:b..l
	(detected by 0, t=10502 jiffies, g=9217, q=176)
task:kworker/u4:6    state:R  running task     stack:23552 pid: 4273 ppid:     2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:inet_twsk_purge+0x8c3/0x9d0 net/ipv4/inet_timewait_sock.c:309
Code: f8 ff ff e8 0f 05 61 01 89 c3 31 ff 89 c6 e8 f4 38 a2 f8 85 db 74 15 e8 7b e9 8c f8 84 c0 74 18 e8 82 35 a2 f8 4c 8b 64 24 20 <eb> 65 e8 76 35 a2 f8 4c 8b 64 24 20 eb 59 e8 da 04 61 01 89 c3 31
RSP: 0018:ffffc900032bfa40 EFLAGS: 00000293
RAX: ffffffff88de500e RBX: 0000000000000001 RCX: ffff8880193e5940
RDX: 0000000000000000 RSI: ffffffff8af9f2a0 RDI: ffffffff8af9f260
RBP: ffffc900032bfb50 R08: ffffffff88de4ffc R09: fffffbfff2131821
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffffff96e87740
R13: 000000000003b4b6 R14: dffffc0000000000 R15: ffff88802cdda5b0
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x886/0xc90 net/core/net_namespace.c:618
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 9964 jiffies! g9217 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:26144 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562