rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4542/1:b..l
	(detected by 0, t=10502 jiffies, g=44493, q=159 ncpus=2)
task:kworker/u4:15   state:R  running task     stack:22888 pid:4542  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:792 [inline]
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
RIP: 0010:batadv_nc_worker+0xef/0x600 net/batman-adv/network-coding.c:719
Code: 8a f7 4c 8d 2d 00 00 00 00 48 c7 c7 e0 a9 b2 8c 31 f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 41 55 e8 25 ac 81 f7 48 83 c4 08 <e8> 7c 03 36 00 89 c3 31 ff 89 c6 e8 61 8e 9f f7 85 db 74 10 e8 e8
RSP: 0018:ffffc90004cbfbe0 EFLAGS: 00000292
RAX: 7daf071355d3d200 RBX: ffff888059363940 RCX: 7daf071355d3d200
RDX: 0000000000000000 RSI: ffffffff8a8c1480 RDI: ffffffff8adefae0
RBP: ffff888055d4c318 R08: dffffc0000000000 R09: fffffbfff215c249
R10: fffffbfff215c249 R11: 1ffffffff215c248 R12: dffffc0000000000
R13: ffffffff89e144ee R14: ffff8880555b4c80 R15: 0000000000000063
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread starved for 10527 jiffies! g44493 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:26912 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </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 default_idle+0xb/0x10 arch/x86/kernel/process.c:741