rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8480/1:b..l
	(detected by 1, t=10502 jiffies, g=75481, q=3 ncpus=2)
task:kworker/u4:20   state:R  running task     stack:23952 pid:8480  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:791 [inline]
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
RIP: 0010:batadv_nc_worker+0xeb/0x600 net/batman-adv/network-coding.c:719
Code: 2b e8 49 50 76 f7 4c 8d 2d 00 00 00 00 48 c7 c7 a0 d5 b2 8c 31 f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 41 55 e8 95 52 6d f7 <48> 83 c4 08 e8 3c e1 36 00 89 c3 31 ff 89 c6 e8 21 8e 8b f7 85 db
RSP: 0018:ffffc9000d257bd8 EFLAGS: 00000246
RAX: cb2132d0ac37a300 RBX: ffff888078277e80 RCX: cb2132d0ac37a300
RDX: 0000000000000000 RSI: ffffffff8a8c2220 RDI: ffffffff8adf0d20
RBP: ffff888057d844c0 R08: dffffc0000000000 R09: 1ffffffff215ee48
R10: dffffc0000000000 R11: fffffbfff215ee49 R12: dffffc0000000000
R13: ffffffff89f6e99e R14: ffff888076238c80 R15: 0000000000000098
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 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 10523 jiffies! g75481 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:27760 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 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 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:741