======================================
| [ 615.203039][ T8094] #0: ffffffffb3e01dc8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink (net/core/rtnetlink.c:3521)
| [ 615.203322][ T8094] #1: ffffffffb3df0a70 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [  615.203637][ T8094]
| [  615.203637][ T8094] stack backtrace:
[  615.204069][ T8094] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  615.204266][ T8094] Call Trace:
[  615.204381][ T8094]  <TASK>
[ 615.204465][ T8094] dump_stack_lvl (lib/dump_stack.c:123)
[ 615.204636][ T8094] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 615.204804][ T8094] validate_chain (kernel/locking/lockdep.c:3894)
[ 615.204970][ T8094] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 615.205125][ T8094] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228)
[ 615.205277][ T8094] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 615.205404][ T8094] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 615.205559][ T8094] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 615.205722][ T8094] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 615.205945][ T8094] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 615.206105][ T8094] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 615.206267][ T8094] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 615.206420][ T8094] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 615.206578][ T8094] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 615.206786][ T8094] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 615.206917][ T8094] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 615.207105][ T8094] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 615.207258][ T8094] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4339 kernel/locking/lockdep.c:4406)
[ 615.207456][ T8094] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 615.207609][ T8094] __netdev_upper_dev_unlink (net/core/dev.c:8000 (discriminator 11) net/core/dev.c:8017 (discriminator 11) net/core/dev.c:8167 (discriminator 11))
[ 615.207774][ T8094] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 615.207972][ T8094] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 615.208130][ T8094] ? del_nbp (net/bridge/br_if.c:215 net/bridge/br_if.c:359)
[ 615.208249][ T8094] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228)
[ 615.208405][ T8094] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 615.208556][ T8094] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 615.208760][ T8094] ? mutex_spin_on_owner (kernel/locking/mutex.c:332)
[ 615.208921][ T8094] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 615.209081][ T8094] ? nbp_backup_change (net/bridge/br_if.c:185 (discriminator 9))
[ 615.209233][ T8094] del_nbp (net/bridge/br_if.c:365)
[ 615.209357][ T8094] br_del_if (net/bridge/br_if.c:741)
[ 615.209473][ T8094] br_device_event (net/bridge/br.c:123)
[ 615.209624][ T8094] ? __pfx_br_device_event (net/bridge/br.c:29)
[ 615.209788][ T8094] ? packet_notifier (net/packet/af_packet.c:4282)
[ 615.209950][ T8094] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 615.210106][ T8094] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 615.210261][ T8094] unregister_netdevice_many_notify (net/core/dev.c:11575)
[ 615.210457][ T8094] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11516)
[ 615.210659][ T8094] ? rtnl_dellink (net/core/rtnetlink.c:3521)
[ 615.210892][ T8094] ? sock_def_readable (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/sock.c:3479)
[ 615.211139][ T8094] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 615.211344][ T8094] ? unregister_netdevice_queue (net/core/dev.c:11501)
[ 615.211532][ T8094] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11500)
[ 615.211732][ T8094] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11500)
[ 615.211935][ T8094] rtnl_dellink (net/core/rtnetlink.c:3487 net/core/rtnetlink.c:3527)
[ 615.212094][ T8094] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3493)
[ 615.212276][ T8094] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 615.212429][ T8094] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 615.212583][ T8094] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6909)
[ 615.212742][ T8094] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 615.212901][ T8094] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 615.213053][ T8094] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6909)
[ 615.213202][ T8094] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3493)
[ 615.213360][ T8094] rtnetlink_rcv_msg (net/core/rtnetlink.c:6911)
[ 615.213513][ T8094] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6814)
[ 615.213670][ T8094] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228)
[ 615.213834][ T8094] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 615.213958][ T8094] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 615.214110][ T8094] netlink_rcv_skb (net/netlink/af_netlink.c:2543)
[ 615.214266][ T8094] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6814)
[ 615.214421][ T8094] ? __pfx_netlink_rcv_skb (net/netlink/af_netlink.c:2520)
[ 615.214590][ T8094] ? netlink_deliver_tap (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/netlink/af_netlink.c:340)
[ 615.214760][ T8094] ? netlink_deliver_tap (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 ./include/net/netns/generic.h:48 net/netlink/af_netlink.c:333)
[ 615.214919][ T8094] netlink_unicast (net/netlink/af_netlink.c:1322 net/netlink/af_netlink.c:1348)
[ 615.215073][ T8094] ? __pfx_netlink_unicast (net/netlink/af_netlink.c:1333)
[ 615.215225][ T8094] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 615.215394][ T8094] netlink_sendmsg (net/netlink/af_netlink.c:1892)
[ 615.215576][ T8094] ? __pfx_netlink_sendmsg (net/netlink/af_netlink.c:1811)
[ 615.215758][ T8094] ____sys_sendmsg (net/socket.c:711 net/socket.c:726 net/socket.c:2594)
[ 615.215925][ T8094] ? __pfx_____sys_sendmsg (net/socket.c:2540)
[ 615.216076][ T8094] ? __pfx_copy_msghdr_from_user (net/socket.c:2520)
[ 615.216272][ T8094] ___sys_sendmsg (net/socket.c:2650)
[ 615.216424][ T8094] ? __pfx____sys_sendmsg (net/socket.c:2637)
[ 615.216580][ T8094] ? kasan_save_stack (mm/kasan/common.c:49)
[ 615.216744][ T8094] ? kasan_save_stack (mm/kasan/common.c:48)
[ 615.216913][ T8094] ? __kasan_record_aux_stack (mm/kasan/generic.c:544)
[ 615.217067][ T8094] ? __call_rcu_common.constprop.0 (./arch/x86/include/asm/irqflags.h:26 ./arch/x86/include/asm/irqflags.h:87 ./arch/x86/include/asm/irqflags.h:123 kernel/rcu/tree.c:3087)
[ 615.217258][ T8094] ? __x64_sys_close (fs/open.c:1557 fs/open.c:1539 fs/open.c:1539)
[ 615.217412][ T8094] ? do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 615.217568][ T8094] ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 615.217781][ T8094] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 615.217946][ T8094] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 615.218104][ T8094] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 615.218260][ T8094] ? __virt_addr_valid (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:962 ./include/linux/mmzone.h:2058 arch/x86/mm/physaddr.c:65)
[ 615.218418][ T8094] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 615.218567][ T8094] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 615.218766][ T8094] __sys_sendmsg (net/socket.c:2680)
[ 615.218940][ T8094] ? __pfx___sys_sendmsg (net/socket.c:2665)
[ 615.219089][ T8094] ? __pfx_slab_free_after_rcu_debug (mm/slub.c:4643)
[ 615.219299][ T8094] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 615.219452][ T8094] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[  615.219645][ T8094] RIP: 0033:0x7f7179f2a9a7
[ 615.219805][ T8094] Code: 0a 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
All code
========
   0:	0a 00                	or     (%rax),%al
   2:	f7 d8                	neg    %eax
   4:	64 89 02             	mov    %eax,%fs:(%rdx)
   7:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
   e:	eb b9                	jmp    0xffffffffffffffc9
  10:	0f 1f 00             	nopl   (%rax)
  13:	f3 0f 1e fa          	endbr64
  17:	64 8b 04 25 18 00 00 	mov    %fs:0x18,%eax
  1e:	00 
  1f:	85 c0                	test   %eax,%eax
  21:	75 10                	jne    0x33
  23:	b8 2e 00 00 00       	mov    $0x2e,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 51                	ja     0x83
  32:	c3                   	ret
  33:	48 83 ec 28          	sub    $0x28,%rsp
  37:	89 54 24 1c          	mov    %edx,0x1c(%rsp)
  3b:	48 89 74 24 10       	mov    %rsi,0x10(%rsp)

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 51                	ja     0x59
   8:	c3                   	ret
   9:	48 83 ec 28          	sub    $0x28,%rsp
   d:	89 54 24 1c          	mov    %edx,0x1c(%rsp)
  11:	48 89 74 24 10       	mov    %rsi,0x10(%rsp)
[  615.220346][ T8094] RSP: 002b:00007ffcb077e7c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[  615.220576][ T8094] RAX: ffffffffffffffda RBX: 00007ffcb077ef00 RCX: 00007f7179f2a9a7
[  615.220805][ T8094] RDX: 0000000000000000 RSI: 00007ffcb077e830 RDI: 0000000000000005
[  615.221038][ T8094] RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000078
[  615.221262][ T8094] R10: 00007f7179de84a8 R11: 0000000000000246 R12: 0000000000000001


Finger prints:
print_deadlock_bug:validate_chain:__lock_acquire:down_read:blocking_notifier_call_chain