rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P61/1:b..l P8908/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=60989, q=208 ncpus=2)
task:kworker/u8:9    state:R  running task     stack:25168 pid:8908  tgid:8908  ppid:2      flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5409 [inline]
 __schedule+0xf15/0x5d00 kernel/sched/core.c:6746
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7068
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:173 [inline]
RIP: 0010:write_comp_data+0x11/0x90 kernel/kcov.c:236
Code: cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 49 89 d2 49 89 f8 49 89 f1 65 48 8b 15 ff 1b 76 7e <65> 8b 05 00 1c 76 7e a9 00 01 ff 00 74 0f f6 c4 01 74 59 8b 82 14
RSP: 0018:ffffc9000416faa8 EFLAGS: 00000202
RAX: ffff888149fe5978 RBX: 0000000000000001 RCX: ffffffff8941e844
RDX: ffff888067bc9e00 RSI: 0000000000000000 RDI: 0000000000000005
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: fffffbfff2946128
R13: 000000000007cb2f R14: ffffffff94a30940 R15: 00000000000f965f
 inet_twsk_purge+0x184/0x8f0 net/ipv4/inet_timewait_sock.c:279
 ops_exit_list+0x128/0x180 net/core/net_namespace.c:175
 cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:637
 process_one_work+0x9a9/0x1ac0 kernel/workqueue.c:3254
 process_scheduled_works kernel/workqueue.c:3335 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
task:kworker/u8:4    state:R  running task     stack:24304 pid:61    tgid:61    ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5409 [inline]
 __schedule+0xf15/0x5d00 kernel/sched/core.c:6746
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7068
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:409 [inline]
RIP: 0010:batadv_nc_worker+0x1a3/0x10f0 net/batman-adv/network-coding.c:719
Code: c6 e8 71 7f ed f6 45 85 ff 58 0f 85 fa 0a 00 00 e8 82 84 ed f6 48 89 d8 48 c1 e8 03 42 80 3c 30 00 0f 85 47 0e 00 00 4c 8b 2b <4d> 85 ed 0f 84 0a 07 00 00 e8 5f 84 ed f6 49 81 ed c8 01 00 00 0f
RSP: 0018:ffffc900015c7b98 EFLAGS: 00000246
RAX: 1ffff11005898158 RBX: ffff88802c4c0ac0 RCX: ffffffff8aa048d9
RDX: ffff888017321e00 RSI: ffffffff8aa03dce RDI: 0000000000000001
RBP: 0000000000000158 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000002 R12: ffff88804890c640
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000001
 process_one_work+0x9a9/0x1ac0 kernel/workqueue.c:3254
 process_scheduled_works kernel/workqueue.c:3335 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: rcu_preempt kthread starved for 10431 jiffies! g60989 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:28032 pid:16    tgid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5409 [inline]
 __schedule+0xf15/0x5d00 kernel/sched/core.c:6746
 __schedule_loop kernel/sched/core.c:6823 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6838
 schedule_timeout+0x136/0x2a0 kernel/time/timer.c:2582
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:1663
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:1862
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </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:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:112