rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P144/1:b..l
	(detected by 1, t=10502 jiffies, g=16009, q=249)
task:kworker/u4:1    state:R  running task     stack:22824 pid:  144 ppid:     2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:check_kcov_mode kernel/kcov.c:174 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x2c/0x80 kernel/kcov.c:293
Code: 04 24 65 48 8b 0d 74 a1 8a 7e 65 8b 15 75 a1 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 5b 83 b9 34 16 00 00 00 74 52 <8b> 91 10 16 00 00 83 fa 03 75 47 48 8b 91 18 16 00 00 44 8b 89 14
RSP: 0018:ffffc9000169fa38 EFLAGS: 00000246
RAX: ffffffff8854d625 RBX: 0000000000000001 RCX: ffff888017d95940
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000169fb50 R08: dffffc0000000000 R09: fffffbfff1ff7619
R10: fffffbfff1ff7619 R11: 1ffffffff1ff7618 R12: 0000000000002100
R13: dffffc0000000000 R14: ffff88814d010800 R15: ffffffff8d4135e0
 rcu_read_unlock include/linux/rcupdate.h:768 [inline]
 inet_twsk_purge+0x6f5/0x810 net/ipv4/inet_timewait_sock.c:309
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x77b/0xb80 net/core/net_namespace.c:635
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 9918 jiffies! g16009 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:27584 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 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 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:729