rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4027/1:b..l P9/1:b..l
	(detected by 0, t=10502 jiffies, g=7181, q=599 ncpus=2)
task:kworker/u4:0    state:R  running task     stack:24568 pid:9     ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6873
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653
RIP: 0010:lock_acquire+0x9a/0x5a0 kernel/locking/lockdep.c:5630
Code: ec 03 48 b8 f1 f1 f1 f1 00 f2 f2 f2 4b 89 04 2c 43 c7 44 2c 09 f2 f2 f2 00 43 c7 44 2c 11 f3 f3 f3 f3 66 43 c7 44 2c 15 f3 f3 <43> c6 44 2c 17 f3 0f 1f 44 00 00 65 8b 1d 04 ad 97 7e 48 c7 c0 78
RSP: 0018:ffffc900000e7a80 EFLAGS: 00000a02
RAX: f2f2f200f1f1f1f1 RBX: ffff88805cad9fc0 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8d32ad40
RBP: ffffc900000e7be0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff9200001cf58
R13: dffffc0000000000 R14: 0000000000000000 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xe8/0x610 net/batman-adv/network-coding.c:719
 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
task:modprobe        state:R  running task     stack:23880 pid:4027  ppid:3720   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 preempt_schedule_notrace+0xf8/0x140 kernel/sched/core.c:6823
 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 rcu_is_watching+0x76/0xb0 kernel/rcu/tree.c:722
 rcu_read_unlock include/linux/rcupdate.h:820 [inline]
 is_bpf_text_address+0x1f8/0x2a0 kernel/bpf/core.c:733
 kernel_text_address+0x9f/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x40 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf3/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook mm/slub.c:1750 [inline]
 slab_free mm/slub.c:3661 [inline]
 kmem_cache_free+0x292/0x510 mm/slub.c:3683
 anon_vma_chain_free mm/rmap.c:146 [inline]
 unlink_anon_vmas+0x59a/0x5e0 mm/rmap.c:446
 free_pgtables+0x229/0x4f0 mm/memory.c:416
 exit_mmap+0x3bb/0x9f0 mm/mmap.c:3237
 __mmput+0x115/0x3c0 kernel/fork.c:1199
 exit_mm+0x226/0x300 kernel/exit.c:565
 do_exit+0x9f6/0x26a0 kernel/exit.c:858
 do_group_exit+0x202/0x2b0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f800dd0da90
RSP: 002b:00007ffd8292f3c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f800ddfe860 RCX: 00007f800dd0da90
RDX: 00000000000000e7 RSI: 000000000000003c RDI: 0000000000000001
RBP: 00007f800ddfe860 R08: 00007ffd8292f240 R09: 00007ffd8292f320
R10: 00007ffd8292f280 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f800de02658 R15: 0000000000000001
 </TASK>
rcu: rcu_preempt kthread starved for 9571 jiffies! g7181 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:27160 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 schedule+0xbf/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 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 acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567