======================================
| [  110.446197][    C2] page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)
| [  110.446558][    C2] ------------[ cut here ]------------
| [  110.446754][    C2] kernel BUG at include/linux/mm.h:1140!
| [  110.446972][    C2] Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
[  110.447528][    C2] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 110.447928][ C2] RIP: 0010:__free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 110.448128][ C2] Code: 0f 94 c3 e9 ba fe ff ff 48 c7 c6 a0 18 58 92 4c 89 e7 e8 df bf f4 ff 90 0f 0b 48 c7 c6 40 29 58 92 4c 89 e7 e8 cd bf f4 ff 90 <0f> 0b 48 89 ef e8 72 03 09 00 e9 c5 fe ff ff e8 98 03 09 00 e9 35
All code
========
   0:	0f 94 c3             	sete   %bl
   3:	e9 ba fe ff ff       	jmp    0xfffffffffffffec2
   8:	48 c7 c6 a0 18 58 92 	mov    $0xffffffff925818a0,%rsi
   f:	4c 89 e7             	mov    %r12,%rdi
  12:	e8 df bf f4 ff       	call   0xfffffffffff4bff6
  17:	90                   	nop
  18:	0f 0b                	ud2
  1a:	48 c7 c6 40 29 58 92 	mov    $0xffffffff92582940,%rsi
  21:	4c 89 e7             	mov    %r12,%rdi
  24:	e8 cd bf f4 ff       	call   0xfffffffffff4bff6
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	48 89 ef             	mov    %rbp,%rdi
  2f:	e8 72 03 09 00       	call   0x903a6
  34:	e9 c5 fe ff ff       	jmp    0xfffffffffffffefe
  39:	e8 98 03 09 00       	call   0x903d6
  3e:	e9                   	.byte 0xe9
  3f:	35                   	.byte 0x35

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	48 89 ef             	mov    %rbp,%rdi
   5:	e8 72 03 09 00       	call   0x9037c
   a:	e9 c5 fe ff ff       	jmp    0xfffffffffffffed4
   f:	e8 98 03 09 00       	call   0x903ac
  14:	e9                   	.byte 0xe9
  15:	35                   	.byte 0x35
[  110.448803][    C2] RSP: 0018:ffffc90000217cb0 EFLAGS: 00010246
[  110.449040][    C2] RAX: 000000000000003e RBX: 0000000000000000 RCX: 1ffffffff263b43c
[  110.449304][    C2] RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001
[  110.449565][    C2] RBP: ffffea0000146474 R08: 0000000000000000 R09: fffffbfff263b43c
[  110.449840][    C2] R10: 0000000000000003 R11: 205d324320202020 R12: ffffea0000146440
[  110.450101][    C2] R13: ffffc90000217d78 R14: 0000000000000000 R15: 0000000000000008
[  110.450399][    C2] FS:  0000000000000000(0000) GS:ffff888036100000(0000) knlGS:0000000000000000
[  110.450787][    C2] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  110.451008][    C2] CR2: 00007f9289e72270 CR3: 000000000a73a005 CR4: 0000000000772ef0
[  110.451274][    C2] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  110.451564][    C2] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  110.451860][    C2] PKRU: 55555554
[  110.452015][    C2] Call Trace:
[  110.452167][    C2]  <TASK>
[ 110.452282][ C2] ? die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434 arch/x86/kernel/dumpstack.c:447) 
[ 110.452440][ C2] ? do_trap (arch/x86/kernel/traps.c:156 arch/x86/kernel/traps.c:197) 
[ 110.452589][ C2] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 110.452786][ C2] ? do_error_trap (./arch/x86/include/asm/traps.h:58 arch/x86/kernel/traps.c:218) 
[ 110.452970][ C2] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 110.453152][ C2] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 110.453342][ C2] ? handle_invalid_op (arch/x86/kernel/traps.c:256) 
[ 110.453527][ C2] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 110.453709][ C2] ? exc_invalid_op (arch/x86/kernel/traps.c:315) 
[ 110.453934][ C2] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621) 
[ 110.454126][ C2] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 110.454321][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2567) 
[ 110.454528][ C2] neigh_hash_free_rcu (net/core/neighbour.c:554) 
[ 110.454728][ C2] rcu_do_batch (kernel/rcu/tree.c:2567) 
[ 110.454913][ C2] ? __pfx___lock_release (kernel/locking/lockdep.c:5477) 
[ 110.455108][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2491) 
[ 110.455350][ C2] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4339 kernel/locking/lockdep.c:4406) 
[ 110.455604][ C2] rcu_core (kernel/rcu/tree.c:2825) 
[ 110.455773][ C2] handle_softirqs (kernel/softirq.c:554) 
[ 110.455965][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:920) 
[ 110.456152][ C2] run_ksoftirqd (kernel/softirq.c:411 kernel/softirq.c:928 kernel/softirq.c:919) 
[ 110.456342][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 110.456533][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 110.456719][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 110.456903][ C2] kthread (kernel/kthread.c:389) 
[ 110.457041][ C2] ? __pfx_kthread (kernel/kthread.c:342) 
[ 110.457369][ C2] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 110.457566][ C2] ? __pfx_kthread (kernel/kthread.c:342) 


Finger prints:
__free_pages:neigh_hash_free_rcu:rcu_do_batch:rcu_core:handle_softirqs