rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6362/1:b..l P6360/1:b..l
	(detected by 1, t=10502 jiffies, g=26417, q=235 ncpus=2)
task:kworker/u4:15   state:R  running task     stack:27792 pid:6360  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_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5666
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc9000ce77ac0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 6aac1431b2250200
RDX: 0000000000000000 RSI: ffffffff8a8c2220 RDI: ffffffff8adf0d20
RBP: ffffc9000ce77bc8 R08: dffffc0000000000 R09: 1ffffffff215ee48
R10: dffffc0000000000 R11: fffffbfff215ee49 R12: 0000000000000000
R13: 1ffff920019cef64 R14: 0000000000000246 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+0xeb/0x600 net/batman-adv/network-coding.c:719
 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>
task:udevadm         state:R  running task     stack:23248 pid:6362  ppid:4500   flags:0x00004002
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_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x0/0x4a0 kernel/locking/lockdep.c:5630
Code: 20 8e e8 73 43 6f 00 e9 2b fb ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 65 8b 05 01 33 9e 7e a9 00 ff ff 00 0f 95 c0 c3 <55> 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec e0 00
RSP: 0018:ffffc9000ce57848 EFLAGS: 00000246
RAX: 0000000000000001 RBX: ffffffff81da1b40 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cb2d5a0
RBP: 0000000000000dc0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1c3fbde R12: 0000000000000000
R13: 00000000000001c8 R14: ffff888025698528 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 get_obj_cgroup_from_current+0xec/0x280 mm/memcontrol.c:3019
 memcg_slab_pre_alloc_hook mm/slab.h:485 [inline]
 slab_pre_alloc_hook+0x91/0x310 mm/slab.h:715
 slab_alloc_node mm/slub.c:3279 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x56/0x2f0 mm/slub.c:3383
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 __alloc_file+0x25/0x230 fs/file_table.c:138
 alloc_empty_file+0x90/0x180 fs/file_table.c:187
 path_openat+0x10f/0x2ee0 fs/namei.c:3777
 do_filp_open+0x1f1/0x430 fs/namei.c:3818
 do_sys_openat2+0x150/0x4b0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4efd8a7407
RSP: 002b:00007ffe6c32c6f0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4efe096880 RCX: 00007f4efd8a7407
RDX: 0000000000080000 RSI: 00007f4efe1562e2 RDI: ffffffffffffff9c
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f4efe1563ae
R13: 00007f4efe1563ae R14: 0000000000000001 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 9706 jiffies! g26417 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:27184 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