======================================
| [  250.763191] ------------[ cut here ]------------
| [  250.763776] refcount_t: underflow; use-after-free.
| [  250.764391] WARNING: CPU: 3 PID: 68 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
| [  250.765318] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  250.767167] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  250.768270] Workqueue: netns cleanup_net
[  250.768804] RIP: 0010:refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[ 250.769551] Code: 0b 90 90 c3 cc cc cc cc 80 3d 69 d4 67 01 00 0f 85 75 ff ff ff c6 05 5c d4 67 01 01 90 48 c7 c7 b8 37 53 a5 e8 a1 26 b4 ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 3c d4 67 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 69 d4 67 01 00 	cmpb   $0x0,0x167d469(%rip)        # 0x167d478
   f:	0f 85 75 ff ff ff    	jne    0xffffffffffffff8a
  15:	c6 05 5c d4 67 01 01 	movb   $0x1,0x167d45c(%rip)        # 0x167d478
  1c:	90                   	nop
  1d:	48 c7 c7 b8 37 53 a5 	mov    $0xffffffffa55337b8,%rdi
  24:	e8 a1 26 b4 ff       	call   0xffffffffffb426ca
  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 3c d4 67 01 00 	cmpb   $0x0,0x167d43c(%rip)        # 0x167d476
  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 3c d4 67 01 00 	cmpb   $0x0,0x167d43c(%rip)        # 0x167d44c
  10:	0f 85 4a ff ff ff    	jne    0xffffffffffffff60
[  250.771664] RSP: 0018:ffffbd6740263d78 EFLAGS: 00010286
[  250.772380] RAX: 0000000000000000 RBX: ffff9dc843f92000 RCX: 00000000ffffdfff
[  250.773095] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  250.773558] RBP: ffff9dc843f92610 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  250.773924] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc843f92000
[  250.774316] R13: ffffbd6740263e08 R14: ffff9dc843f92b80 R15: ffffffffa6e78f90
[  250.774731] FS:  0000000000000000(0000) GS:ffff9dc87ed80000(0000) knlGS:0000000000000000
[  250.775379] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  250.775745] CR2: 00007f2f91a5ea30 CR3: 0000000003dd6004 CR4: 0000000000770ef0
[  250.776146] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  250.776668] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  250.777235] PKRU: 55555554
[  250.777452] Call Trace:
[  250.777653]  <TASK>
[  250.777839] ? __warn (kernel/panic.c:677) 
[  250.778084] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[  250.778480] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  250.778809] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  250.779135] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  250.779461] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  250.779873] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[  250.780448] ? refcount_warn_saturate (lib/refcount.c:28 (discriminator 3)) 
[  250.780888] br_sysfs_delbr (net/bridge/br_sysfs_br.c:1086) 
[  250.781244] br_dev_delete (net/bridge/br_if.c:396) 
[  250.781581] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  250.781957] cleanup_net (net/core/net_namespace.c:630) 
[  250.782289] ? process_one_work (kernel/workqueue.c:2606) 
[  250.782647] process_one_work (kernel/workqueue.c:2633) 
[  250.783011] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  250.783359] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  250.783723] kthread (kernel/kthread.c:388) 
[  250.783954] ? __pfx_kthread (kernel/kthread.c:341) 
[  250.784279] ret_from_fork (arch/x86/kernel/process.c:147) 
[  250.784565] ? __pfx_kthread (kernel/kthread.c:341) 
[  250.784888] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  250.788708] ------------[ cut here ]------------
| [  250.789001] sysfs group 'bridge' not found for kobject 'br0'
| [  250.789434] WARNING: CPU: 3 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  250.789854] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  250.791420] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  250.792455] Workqueue: netns cleanup_net
[  250.792850] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 250.793343] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  250.794944] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  250.795591] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  250.796512] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  250.797462] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  250.798421] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc843f92610
[  250.799170] R13: ffffbd6740263e08 R14: ffff9dc843f92b80 R15: ffffffffa6e78f90
[  250.799779] FS:  0000000000000000(0000) GS:ffff9dc87ed80000(0000) knlGS:0000000000000000
[  250.800448] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  250.800922] CR2: 00007f2f91a5ea30 CR3: 0000000003dd6004 CR4: 0000000000770ef0
[  250.801462] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  250.802054] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  250.802579] PKRU: 55555554
[  250.802725] Call Trace:
[  250.802890]  <TASK>
[  250.803010] ? __warn (kernel/panic.c:677) 
[  250.803223] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  250.803515] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  250.803711] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  250.803907] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  250.804110] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  250.804335] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  250.804554] br_dev_delete (net/bridge/br_if.c:396) 
[  250.804748] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  250.804988] cleanup_net (net/core/net_namespace.c:630) 
[  250.805181] ? process_one_work (kernel/workqueue.c:2606) 
[  250.805401] process_one_work (kernel/workqueue.c:2633) 
[  250.805616] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  250.805821] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  250.806047] kthread (kernel/kthread.c:388) 
[  250.806215] ? __pfx_kthread (kernel/kthread.c:341) 
[  250.806414] ret_from_fork (arch/x86/kernel/process.c:147) 
[  250.806610] ? __pfx_kthread (kernel/kthread.c:341) 
[  250.806816] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  250.809333] ------------[ cut here ]------------
| [  250.809573] sysfs group 'bridge' not found for kobject 'br0'
| [  250.809887] WARNING: CPU: 3 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  250.810297] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  250.811460] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  250.812041] Workqueue: netns cleanup_net
[  250.812247] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 250.812494] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  250.813425] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  250.813692] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  250.814059] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  250.814421] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  250.814788] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc843f90610
[  250.815152] R13: ffffbd6740263e08 R14: ffff9dc843f90b80 R15: ffffffffa6e78f90
[  250.815512] FS:  0000000000000000(0000) GS:ffff9dc87ed80000(0000) knlGS:0000000000000000
[  250.815927] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  250.816221] CR2: 00007f2f91a5ea30 CR3: 0000000003dd6004 CR4: 0000000000770ef0
[  250.816584] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  250.816964] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  250.817334] PKRU: 55555554
[  250.817479] Call Trace:
[  250.817612]  <TASK>
[  250.817727] ? __warn (kernel/panic.c:677) 
[  250.817905] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  250.818124] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  250.818321] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  250.818507] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  250.818709] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  250.818939] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  250.819158] br_dev_delete (net/bridge/br_if.c:396) 
[  250.819349] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  250.819581] cleanup_net (net/core/net_namespace.c:630) 
[  250.819773] ? process_one_work (kernel/workqueue.c:2606) 
[  250.819995] process_one_work (kernel/workqueue.c:2633) 
[  250.820208] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  250.820407] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  250.820630] kthread (kernel/kthread.c:388) 
[  250.820807] ? __pfx_kthread (kernel/kthread.c:341) 
[  250.821005] ret_from_fork (arch/x86/kernel/process.c:147) 
[  250.821197] ? __pfx_kthread (kernel/kthread.c:341) 
[  250.821394] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  270.440027] ------------[ cut here ]------------
| [  270.440528] sysfs group 'bridge' not found for kobject 'br0'
| [  270.441167] WARNING: CPU: 3 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  270.442140] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  270.443953] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  270.444746] Workqueue: netns cleanup_net
[  270.445111] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 270.445685] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  270.447412] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  270.447808] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  270.448678] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  270.449557] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  270.450385] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc841934610
[  270.451241] R13: ffffbd6740263e08 R14: ffff9dc841934b80 R15: ffff9dc843c4c550
[  270.452131] FS:  0000000000000000(0000) GS:ffff9dc87ed80000(0000) knlGS:0000000000000000
[  270.453204] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  270.453900] CR2: 00007f9a335af000 CR3: 0000000003dd6005 CR4: 0000000000770ef0
[  270.454691] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  270.455470] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  270.456164] PKRU: 55555554
[  270.456486] Call Trace:
[  270.456736]  <TASK>
[  270.456976] ? __warn (kernel/panic.c:677) 
[  270.457358] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  270.457833] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  270.458193] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  270.458557] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  270.459005] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  270.459337] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  270.459627] br_dev_delete (net/bridge/br_if.c:396) 
[  270.459910] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  270.460261] cleanup_net (net/core/net_namespace.c:630) 
[  270.460554] ? process_one_work (kernel/workqueue.c:2606) 
[  270.460960] process_one_work (kernel/workqueue.c:2633) 
[  270.461241] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  270.461504] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  270.461806] kthread (kernel/kthread.c:388) 
[  270.462108] ? __pfx_kthread (kernel/kthread.c:341) 
[  270.462523] ret_from_fork (arch/x86/kernel/process.c:147) 
[  270.462917] ? __pfx_kthread (kernel/kthread.c:341) 
[  270.463321] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  270.547011] ------------[ cut here ]------------
| [  270.547491] sysfs group 'bridge' not found for kobject 'br0'
| [  270.548194] WARNING: CPU: 3 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  270.549190] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  270.552145] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  270.553463] Workqueue: netns cleanup_net
[  270.553938] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 270.554481] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  270.556540] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  270.556953] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  270.557492] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  270.558153] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  270.558670] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc8428aa610
[  270.559310] R13: ffffbd6740263e08 R14: ffff9dc8428aab80 R15: ffff9dc842bac550
[  270.559977] FS:  0000000000000000(0000) GS:ffff9dc87ed80000(0000) knlGS:0000000000000000
[  270.560808] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  270.561483] CR2: 00007f9a335af000 CR3: 000000000b060004 CR4: 0000000000770ef0
[  270.562317] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  270.563170] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  270.564107] PKRU: 55555554
[  270.564494] Call Trace:
[  270.564882]  <TASK>
[  270.565198] ? __warn (kernel/panic.c:677) 
[  270.565619] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  270.566205] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  270.566681] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  270.567037] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  270.567523] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  270.567966] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  270.568418] br_dev_delete (net/bridge/br_if.c:396) 
[  270.568798] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  270.569242] cleanup_net (net/core/net_namespace.c:630) 
[  270.569644] ? process_one_work (kernel/workqueue.c:2606) 
[  270.570089] process_one_work (kernel/workqueue.c:2633) 
[  270.570436] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  270.570718] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  270.571068] kthread (kernel/kthread.c:388) 
[  270.571328] ? __pfx_kthread (kernel/kthread.c:341) 
[  270.571589] ret_from_fork (arch/x86/kernel/process.c:147) 
[  270.571849] ? __pfx_kthread (kernel/kthread.c:341) 
[  270.572108] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  291.885161] ------------[ cut here ]------------
| [  291.885577] sysfs group 'bridge' not found for kobject 'br0'
| [  291.886102] WARNING: CPU: 0 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  291.886740] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  291.888545] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  291.889232] Workqueue: netns cleanup_net
[  291.889457] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 291.889741] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  291.890712] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  291.891037] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  291.891409] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  291.891799] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  291.892203] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc842a88610
[  291.892590] R13: ffffbd6740263e08 R14: ffff9dc842a88b80 R15: ffff9dc8426e2e50
[  291.892982] FS:  0000000000000000(0000) GS:ffff9dc87ec00000(0000) knlGS:0000000000000000
[  291.893422] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  291.893753] CR2: 00007ff1be7abd40 CR3: 0000000003dd6001 CR4: 0000000000770ef0
[  291.894154] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  291.894534] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  291.894928] PKRU: 55555554
[  291.895124] Call Trace:
[  291.895290]  <TASK>
[  291.895418] ? __warn (kernel/panic.c:677) 
[  291.895620] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  291.895879] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  291.896109] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  291.896305] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  291.896532] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  291.896796] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  291.897058] br_dev_delete (net/bridge/br_if.c:396) 
[  291.897274] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  291.897534] cleanup_net (net/core/net_namespace.c:630) 
[  291.897755] ? process_one_work (kernel/workqueue.c:2606) 
[  291.898015] process_one_work (kernel/workqueue.c:2633) 
[  291.898242] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  291.898499] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  291.898761] kthread (kernel/kthread.c:388) 
[  291.898967] ? __pfx_kthread (kernel/kthread.c:341) 
[  291.899235] ret_from_fork (arch/x86/kernel/process.c:147) 
[  291.899456] ? __pfx_kthread (kernel/kthread.c:341) 
[  291.899681] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  291.997033] ------------[ cut here ]------------
| [  291.997326] sysfs group 'bridge' not found for kobject 'br0'
| [  291.997661] WARNING: CPU: 0 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  291.998119] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  291.999425] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  292.000050] Workqueue: netns cleanup_net
[  292.000263] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 292.000516] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  292.001497] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  292.001855] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  292.002262] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  292.002699] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  292.003162] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc8423fc610
[  292.003602] R13: ffffbd6740263e08 R14: ffff9dc8423fcb80 R15: ffff9dc842ba8050
[  292.004015] FS:  0000000000000000(0000) GS:ffff9dc87ec00000(0000) knlGS:0000000000000000
[  292.004462] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  292.004800] CR2: 00007ff1be7abd40 CR3: 000000000b060005 CR4: 0000000000770ef0
[  292.005237] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  292.005661] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  292.006093] PKRU: 55555554
[  292.006293] Call Trace:
[  292.006457]  <TASK>
[  292.006628] ? __warn (kernel/panic.c:677) 
[  292.006850] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  292.007097] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  292.007343] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  292.007581] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  292.007814] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  292.008055] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  292.008308] br_dev_delete (net/bridge/br_if.c:396) 
[  292.008550] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  292.008842] cleanup_net (net/core/net_namespace.c:630) 
[  292.009071] ? process_one_work (kernel/workqueue.c:2606) 
[  292.009402] process_one_work (kernel/workqueue.c:2633) 
[  292.009661] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  292.009917] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  292.010191] kthread (kernel/kthread.c:388) 
[  292.010406] ? __pfx_kthread (kernel/kthread.c:341) 
[  292.010641] ret_from_fork (arch/x86/kernel/process.c:147) 
[  292.010870] ? __pfx_kthread (kernel/kthread.c:341) 
[  292.011103] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  301.270015] ------------[ cut here ]------------
| [  301.270302] sysfs group 'bridge' not found for kobject 'br0'
| [  301.270709] WARNING: CPU: 2 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  301.271163] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  301.272409] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  301.273053] Workqueue: netns cleanup_net
[  301.273269] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 301.273534] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  301.274510] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  301.274799] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  301.275174] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  301.275554] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  301.275938] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc841c14610
[  301.276306] R13: ffffbd6740263e08 R14: ffff9dc841c14b80 R15: ffff9dc8426e4550
[  301.276683] FS:  0000000000000000(0000) GS:ffff9dc87ed00000(0000) knlGS:0000000000000000
[  301.277200] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  301.277620] CR2: 00007ffe7949fcf8 CR3: 000000000b060004 CR4: 0000000000770ef0
[  301.278175] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  301.278541] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  301.278909] PKRU: 55555554
[  301.279063] Call Trace:
[  301.279204]  <TASK>
[  301.279333] ? __warn (kernel/panic.c:677) 
[  301.279528] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  301.279764] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  301.279979] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  301.280172] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  301.280375] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  301.280608] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  301.280838] br_dev_delete (net/bridge/br_if.c:396) 
[  301.281050] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  301.281296] cleanup_net (net/core/net_namespace.c:630) 
[  301.281499] ? process_one_work (kernel/workqueue.c:2606) 
[  301.281721] process_one_work (kernel/workqueue.c:2633) 
[  301.281950] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  301.282160] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  301.282397] kthread (kernel/kthread.c:388) 
[  301.282572] ? __pfx_kthread (kernel/kthread.c:341) 
[  301.282769] ret_from_fork (arch/x86/kernel/process.c:147) 
[  301.282987] ? __pfx_kthread (kernel/kthread.c:341) 
[  301.283194] ret_from_fork_asm (arch/x86/entry/entry_64.S:250) 
| [  301.419041] ------------[ cut here ]------------
| [  301.419380] sysfs group 'bridge' not found for kobject 'br0'
| [  301.420047] WARNING: CPU: 3 PID: 68 at fs/sysfs/group.c:282 sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
| [  301.421073] Modules linked in: act_gact cls_flower sch_ingress vxlan ip6_udp_tunnel udp_tunnel sha1_generic xfrm_user xt_policy nft_compat nf_tables libcrc32c
[  301.423344] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  301.424859] Workqueue: netns cleanup_net
[  301.425268] RIP: 0010:sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[ 301.425950] Code: 48 89 ef 5d 41 5c e9 7a ad ff ff 48 89 ef e8 12 9b ff ff eb d1 90 49 8b 14 24 48 8b 33 48 c7 c7 a0 cd 52 a5 e8 ac 67 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 7a ad ff ff       	jmp    0xffffffffffffad85
   b:	48 89 ef             	mov    %rbp,%rdi
   e:	e8 12 9b ff ff       	call   0xffffffffffff9b25
  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 a0 cd 52 a5 	mov    $0xffffffffa552cda0,%rdi
  24:	e8 ac 67 c5 ff       	call   0xffffffffffc567d5
  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)
	...
[  301.428516] RSP: 0018:ffffbd6740263d70 EFLAGS: 00010286
[  301.429307] RAX: 0000000000000000 RBX: ffffffffa51472c0 RCX: 00000000ffffdfff
[  301.430217] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001
[  301.430758] RBP: 0000000000000000 R08: ffffffffa5978508 R09: 00000000ffffdfff
[  301.431277] R10: ffffffffa5898520 R11: ffffffffa5948520 R12: ffff9dc841c10610
[  301.431752] R13: ffffbd6740263e08 R14: ffff9dc841c10b80 R15: ffffffffa6e78f90
[  301.432241] FS:  0000000000000000(0000) GS:ffff9dc87ed80000(0000) knlGS:0000000000000000
[  301.432897] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  301.433463] CR2: 00007f2f91a5ea30 CR3: 000000000b060006 CR4: 0000000000770ef0
[  301.434031] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  301.434527] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  301.435154] PKRU: 55555554
[  301.435491] Call Trace:
[  301.435805]  <TASK>
[  301.436035] ? __warn (kernel/panic.c:677) 
[  301.436419] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  301.436973] ? report_bug (lib/bug.c:201 lib/bug.c:219) 
[  301.437403] ? handle_bug (arch/x86/kernel/traps.c:238) 
[  301.437848] ? exc_invalid_op (arch/x86/kernel/traps.c:259 (discriminator 1)) 
[  301.438288] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[  301.438759] ? sysfs_remove_group (fs/sysfs/group.c:282 (discriminator 1)) 
[  301.439191] br_dev_delete (net/bridge/br_if.c:396) 
[  301.439588] br_net_exit_batch_rtnl (net/bridge/br.c:369) 
[  301.440283] cleanup_net (net/core/net_namespace.c:630) 
[  301.440766] ? process_one_work (kernel/workqueue.c:2606) 
[  301.441356] process_one_work (kernel/workqueue.c:2633) 
[  301.441937] worker_thread (kernel/workqueue.c:2700 kernel/workqueue.c:2787) 
[  301.442566] ? __pfx_worker_thread (kernel/workqueue.c:2733) 
[  301.443199] kthread (kernel/kthread.c:388) 
[  301.443795] ? __pfx_kthread (kernel/kthread.c:341) 
[  301.444290] ret_from_fork (arch/x86/kernel/process.c:147) 
[  301.444808] ? __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
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
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
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