======================================
| [  832.523236] ------------[ cut here ]------------
| [  832.523618] refcount_t: underflow; use-after-free.
| [  832.524051] WARNING: CPU: 1 PID: 11 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
| [  832.524708] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel bridge stp llc act_gact cls_flower sch_ingress 8021q ip_gre gre vrf veth
[  832.525869] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  832.526503] Workqueue: netns cleanup_net
[  832.526729] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[ 832.527031] Code: 0b 90 90 c3 cc cc cc cc 80 3d a1 b9 66 01 00 0f 85 75 ff ff ff c6 05 94 b9 66 01 01 90 48 c7 c7 c8 70 6f 83 e8 71 92 b4 ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 74 b9 66 01 00 0f 85 4a ff ff ff
All code
========
   0:	0b 90 90 c3 cc cc    	or     -0x33333c70(%rax),%edx
   6:	cc                   	int3
   7:	cc                   	int3
   8:	80 3d a1 b9 66 01 00 	cmpb   $0x0,0x166b9a1(%rip)        # 0x166b9b0
   f:	0f 85 75 ff ff ff    	jne    0xffffffffffffff8a
  15:	c6 05 94 b9 66 01 01 	movb   $0x1,0x166b994(%rip)        # 0x166b9b0
  1c:	90                   	nop
  1d:	48 c7 c7 c8 70 6f 83 	mov    $0xffffffff836f70c8,%rdi
  24:	e8 71 92 b4 ff       	call   0xffffffffffb4929a
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	c3                   	ret
  2f:	cc                   	int3
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	80 3d 74 b9 66 01 00 	cmpb   $0x0,0x166b974(%rip)        # 0x166b9ae
  3a:	0f 85 4a ff ff ff    	jne    0xffffffffffffff8a

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	c3                   	ret
   5:	cc                   	int3
   6:	cc                   	int3
   7:	cc                   	int3
   8:	cc                   	int3
   9:	80 3d 74 b9 66 01 00 	cmpb   $0x0,0x166b974(%rip)        # 0x166b984
  10:	0f 85 4a ff ff ff    	jne    0xffffffffffffff60
[  832.528073] RSP: 0018:ffffae4a00063d78 EFLAGS: 00010286
[  832.528397] RAX: 0000000000000000 RBX: ffff8a058190e000 RCX: 00000000ffffdfff
[  832.528835] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  832.529239] RBP: ffff8a058190e5f8 R08: ffffffff83b64508 R09: 00000000ffffdfff
[  832.529668] R10: ffffffff83a84520 R11: ffffffff83b34520 R12: ffff8a058190e000
[  832.530056] R13: ffffae4a00063e08 R14: ffff8a058190eb60 R15: ffff8a0585d30050
[  832.530467] FS:  0000000000000000(0000) GS:ffff8a05bec80000(0000) knlGS:0000000000000000
[  832.530927] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  832.531236] CR2: 00007fa13346e0c8 CR3: 000000000282e004 CR4: 00000000001706f0
[  832.531622] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  832.532015] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  832.532411] Call Trace:
[  832.532554]  <TASK>
[  832.532680] ? __warn (kernel/panic.c:677) 
[  832.532863] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[  832.533124] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  832.533337] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  832.533570] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  832.533779] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  832.534023] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[  832.534280] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[  832.534548] br_sysfs_delbr (net/bridge/br_sysfs_br.c:1086) bridge
[  832.534842] br_dev_delete (net/bridge/br_if.c:396) bridge
[  832.535105] br_net_exit_batch_rtnl (net/bridge/br.c:369) bridge
[  832.535423] cleanup_net (net/core/net_namespace.c:628 (discriminator 2)) 
[  832.535643] ? process_one_work (kernel/workqueue.c:2606) 
[  832.535899] process_one_work (kernel/workqueue.c:2638) 
[  832.536142] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  832.536367] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  832.536619] kthread (kernel/kthread.c:388) 
[  832.536808] ? __pfx_kthread (kernel/kthread.c:341) 
[  832.537043] ret_from_fork (arch/x86/kernel/process.c:153) 
[  832.537245] ? __pfx_kthread (kernel/kthread.c:341) 
[  832.537489] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  832.540260] ------------[ cut here ]------------
| [  832.540540] sysfs group 'bridge' not found for kobject 'br2'
| [  832.540876] WARNING: CPU: 1 PID: 11 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  832.541322] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel bridge stp llc act_gact cls_flower sch_ingress 8021q ip_gre gre vrf veth
[  832.542530] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  832.543161] Workqueue: netns cleanup_net
[  832.543391] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 832.543670] Code: 48 89 ef 5d 41 5c e9 0a ae ff ff 48 89 ef e8 a2 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 b0 06 6f 83 e8 fc b0 c5 ff 90 <0f> 0b 90 90 5b 5d 41 5c c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
All code
========
   0:	48 89 ef             	mov    %rbp,%rdi
   3:	5d                   	pop    %rbp
   4:	41 5c                	pop    %r12
   6:	e9 0a ae ff ff       	jmp    0xffffffffffffae15
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 a2 9b ff ff       	call   0xffffffffffff9bb5
  13:	eb d1                	jmp    0xffffffffffffffe6
  15:	90                   	nop
  16:	49 8b 14 24          	mov    (%r12),%rdx
  1a:	48 8b 33             	mov    (%rbx),%rsi
  1d:	48 c7 c7 b0 06 6f 83 	mov    $0xffffffff836f06b0,%rdi
  24:	e8 fc b0 c5 ff       	call   0xffffffffffc5b125
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	5b                   	pop    %rbx
  2f:	5d                   	pop    %rbp
  30:	41 5c                	pop    %r12
  32:	c3                   	ret
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	66                   	data16
  38:	66                   	data16
  39:	2e                   	cs
  3a:	0f                   	.byte 0xf
  3b:	1f                   	(bad)
  3c:	84 00                	test   %al,(%rax)
	...

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	5b                   	pop    %rbx
   5:	5d                   	pop    %rbp
   6:	41 5c                	pop    %r12
   8:	c3                   	ret
   9:	cc                   	int3
   a:	cc                   	int3
   b:	cc                   	int3
   c:	cc                   	int3
   d:	66                   	data16
   e:	66                   	data16
   f:	2e                   	cs
  10:	0f                   	.byte 0xf
  11:	1f                   	(bad)
  12:	84 00                	test   %al,(%rax)
	...
[  832.544759] RSP: 0018:ffffae4a00063d70 EFLAGS: 00010286
[  832.545051] RAX: 0000000000000000 RBX: ffffffffc04edc60 RCX: 00000000ffffdfff
[  832.545469] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  832.545848] RBP: 0000000000000000 R08: ffffffff83b64508 R09: 00000000ffffdfff
[  832.546254] R10: ffffffff83a84520 R11: ffffffff83b34520 R12: ffff8a058190e5f8
[  832.546706] R13: ffffae4a00063e08 R14: ffff8a058190eb60 R15: ffff8a0585d30050
[  832.547220] FS:  0000000000000000(0000) GS:ffff8a05bec80000(0000) knlGS:0000000000000000
[  832.547846] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  832.548172] CR2: 00007fa13346e0c8 CR3: 000000000282e004 CR4: 00000000001706f0
[  832.548601] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  832.549048] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  832.549499] Call Trace:
[  832.549643]  <TASK>
[  832.549768] ? __warn (kernel/panic.c:677) 
[  832.549960] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  832.550194] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  832.550407] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  832.550605] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  832.550819] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  832.551064] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  832.551296] br_dev_delete (net/bridge/br_if.c:396) bridge
[  832.551562] br_net_exit_batch_rtnl (net/bridge/br.c:369) bridge
[  832.551856] cleanup_net (net/core/net_namespace.c:628 (discriminator 2)) 
[  832.552068] ? process_one_work (kernel/workqueue.c:2606) 
[  832.552312] process_one_work (kernel/workqueue.c:2638) 
[  832.552563] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  832.552796] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  832.553077] kthread (kernel/kthread.c:388) 
[  832.553310] ? __pfx_kthread (kernel/kthread.c:341) 
[  832.553614] ret_from_fork (arch/x86/kernel/process.c:153) 
[  832.553822] ? __pfx_kthread (kernel/kthread.c:341) 
[  832.554036] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  832.661241] ------------[ cut here ]------------
| [  832.661649] sysfs group 'bridge' not found for kobject 'br2'
| [  832.662156] WARNING: CPU: 3 PID: 11 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  832.662741] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel bridge stp llc act_gact cls_flower sch_ingress 8021q ip_gre gre vrf veth
[  832.664206] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  832.665101] Workqueue: netns cleanup_net
[  832.665423] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 832.665814] Code: 48 89 ef 5d 41 5c e9 0a ae ff ff 48 89 ef e8 a2 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 b0 06 6f 83 e8 fc b0 c5 ff 90 <0f> 0b 90 90 5b 5d 41 5c c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
All code
========
   0:	48 89 ef             	mov    %rbp,%rdi
   3:	5d                   	pop    %rbp
   4:	41 5c                	pop    %r12
   6:	e9 0a ae ff ff       	jmp    0xffffffffffffae15
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 a2 9b ff ff       	call   0xffffffffffff9bb5
  13:	eb d1                	jmp    0xffffffffffffffe6
  15:	90                   	nop
  16:	49 8b 14 24          	mov    (%r12),%rdx
  1a:	48 8b 33             	mov    (%rbx),%rsi
  1d:	48 c7 c7 b0 06 6f 83 	mov    $0xffffffff836f06b0,%rdi
  24:	e8 fc b0 c5 ff       	call   0xffffffffffc5b125
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	5b                   	pop    %rbx
  2f:	5d                   	pop    %rbp
  30:	41 5c                	pop    %r12
  32:	c3                   	ret
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	66                   	data16
  38:	66                   	data16
  39:	2e                   	cs
  3a:	0f                   	.byte 0xf
  3b:	1f                   	(bad)
  3c:	84 00                	test   %al,(%rax)
	...

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	90                   	nop
   4:	5b                   	pop    %rbx
   5:	5d                   	pop    %rbp
   6:	41 5c                	pop    %r12
   8:	c3                   	ret
   9:	cc                   	int3
   a:	cc                   	int3
   b:	cc                   	int3
   c:	cc                   	int3
   d:	66                   	data16
   e:	66                   	data16
   f:	2e                   	cs
  10:	0f                   	.byte 0xf
  11:	1f                   	(bad)
  12:	84 00                	test   %al,(%rax)
	...
[  832.667269] RSP: 0018:ffffae4a00063d70 EFLAGS: 00010286
[  832.667684] RAX: 0000000000000000 RBX: ffffffffc04edc60 RCX: 00000000ffffdfff
[  832.668257] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  832.668823] RBP: 0000000000000000 R08: ffffffff83b64508 R09: 00000000ffffdfff
[  832.669408] R10: ffffffff83a84520 R11: ffffffff83b34520 R12: ffff8a05829dc5f8
[  832.669981] R13: ffffae4a00063e08 R14: ffff8a05829dcb60 R15: ffffffff85013dd0
[  832.670551] FS:  0000000000000000(0000) GS:ffff8a05bed80000(0000) knlGS:0000000000000000
[  832.671189] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  832.671646] CR2: 0000560a1bc04dec CR3: 00000000029e8001 CR4: 00000000001706f0
[  832.672220] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  832.672782] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  832.673355] Call Trace:
[  832.673564]  <TASK>
[  832.673748] ? __warn (kernel/panic.c:677) 
[  832.674031] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  832.674370] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  832.674681] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  832.674989] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  832.675307] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  832.675655] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  832.676002] br_dev_delete (net/bridge/br_if.c:396) bridge
[  832.676290] br_net_exit_batch_rtnl (net/bridge/br.c:369) bridge
[  832.676680] cleanup_net (net/core/net_namespace.c:628 (discriminator 2)) 
[  832.676974] ? process_one_work (kernel/workqueue.c:2606) 
[  832.677316] process_one_work (kernel/workqueue.c:2638) 
[  832.677645] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  832.677962] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  832.678315] kthread (kernel/kthread.c:388) 
[  832.678554] ? __pfx_kthread (kernel/kthread.c:341) 
[  832.678761] ret_from_fork (arch/x86/kernel/process.c:153) 
[  832.678976] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
refcount_warn_saturate:br_sysfs_delbr:br_dev_delete:br_net_exit_batch_rtnl
sysfs_remove_group:br_dev_delete:br_net_exit_batch_rtnl:cleanup_net
sysfs_remove_group:br_dev_delete:br_net_exit_batch_rtnl:cleanup_net