rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9668/1:b..l P9741/1:b..l
	(detected by 1, t=10502 jiffies, g=64217, q=133 ncpus=2)
task:syz.6.1283      state:R  running task     stack:26224 pid:9741  ppid:7859   flags:0x00004000
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:trace_lock_acquire include/trace/events/lock.h:24 [inline]
RIP: 0010:lock_acquire+0xdc/0x4a0 kernel/locking/lockdep.c:5633
Code: a3 bb 0c 0f 83 a2 01 00 00 45 89 f4 41 c1 ee 06 4a 8d 3c f5 e8 de 1f 8e be 08 00 00 00 e8 1c 44 6f 00 4c 0f a3 25 bc a1 bb 0c <73> 0d e8 9d 32 08 00 84 c0 0f 84 2e 02 00 00 48 c7 c0 a4 13 20 8e
RSP: 0018:ffffc90004cdf720 EFLAGS: 00000257
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81643d24
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e1fdee8
RBP: ffffc90004cdf838 R08: ffffffff8e1fdeef R09: 1ffffffff1c3fbdd
R10: dffffc0000000000 R11: fffffbfff1c3fbde R12: 0000000000000000
R13: 1ffff9200099bef0 R14: 0000000000000000 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:330 [inline]
 percpu_ref_put+0x2e/0x100 include/linux/percpu-refcount.h:351
 obj_cgroup_put include/linux/memcontrol.h:795 [inline]
 memcg_slab_free_hook+0x16d/0x1f0 mm/slab.h:572
 slab_free mm/slub.c:3682 [inline]
 kmem_cache_free+0xe0/0x290 mm/slub.c:3709
 anon_vma_chain_free mm/rmap.c:146 [inline]
 unlink_anon_vmas+0x2c8/0x660 mm/rmap.c:420
 free_pgtables+0x263/0x400 mm/memory.c:430
 exit_mmap+0x37c/0x960 mm/mmap.c:3260
 __mmput+0x118/0x3c0 kernel/fork.c:1205
 exit_mm+0x1fe/0x2d0 kernel/exit.c:565
 do_exit+0x905/0x2480 kernel/exit.c:867
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 __do_sys_exit_group kernel/exit.c:1033 [inline]
 __se_sys_exit_group kernel/exit.c:1031 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031
 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: 0033:0x7f918099c819
RSP: 002b:00007fffa4232048 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f918099c819
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fffa42320ac R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000055
R13: 00000000000927c0 R14: 0000000000068b32 R15: 00007fffa4232100
 </TASK>
task:kworker/u4:14   state:R  running task     stack:26384 pid:9668  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_read_lock+0x2d/0x50 kernel/rcu/tree_plugin.h:404
Code: 8b 1d 57 35 95 7e 48 81 c3 3c 04 00 00 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 11 ff 03 8b 03 <3d> 00 00 00 40 7d 02 5b c3 0f 0b eb fa 89 d9 80 e1 07 80 c1 03 38
RSP: 0018:ffffc90004437bd0 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffff88802a73bfbc RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffffffff8a8c2220 RDI: ffffffff8adf0d20
RBP: ffff88807c41c010 R08: ffffffff8e1fdeef R09: 1ffffffff1c3fbdd
R10: dffffc0000000000 R11: fffffbfff1c3fbde R12: dffffc0000000000
R13: ffff888058e723d0 R14: ffff88807ca24c80 R15: 0000000000000002
 rcu_read_lock include/linux/rcupdate.h:789 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xc7/0x600 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>
rcu: rcu_preempt kthread starved for 10190 jiffies! g64217 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