======================================
| [ 593.786976][ T8480] #0: ffffffff9e601dc8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink (net/core/rtnetlink.c:3512)
| [ 593.787293][ T8480] #1: ffffffff9e5f0a70 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [  593.787646][ T8480]
| [  593.787646][ T8480] stack backtrace:
[  593.788332][ T8480] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  593.788667][ T8480] Call Trace:
[  593.788883][ T8480]  <TASK>
[ 593.789019][ T8480] dump_stack_lvl (lib/dump_stack.c:123)
[ 593.789239][ T8480] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 593.789424][ T8480] validate_chain (kernel/locking/lockdep.c:3894)
[ 593.789602][ T8480] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 593.789797][ T8480] ? 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)
[ 593.789980][ T8480] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 593.790120][ T8480] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 593.790301][ T8480] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 593.790476][ T8480] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 593.790698][ T8480] ? validate_chain (kernel/locking/lockdep.c:3915)
[ 593.790885][ T8480] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 593.791060][ T8480] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 593.791237][ T8480] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 593.791413][ T8480] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 593.791636][ T8480] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 593.791786][ T8480] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 593.792003][ T8480] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 593.792176][ T8480] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 593.792353][ T8480] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 593.792530][ T8480] __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))
[ 593.792707][ T8480] ? br_fdb_delete_by_port (net/bridge/br_fdb.c:768)
[ 593.792887][ T8480] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 593.793107][ T8480] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 593.793287][ T8480] ? del_nbp (net/bridge/br_if.c:215 net/bridge/br_if.c:359)
[ 593.793423][ T8480] ? 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)
[ 593.793602][ T8480] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 593.793803][ T8480] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 593.794042][ T8480] ? mutex_spin_on_owner (kernel/locking/mutex.c:332)
[ 593.794217][ T8480] ? rtnl_is_locked (net/core/rtnetlink.c:164)
[ 593.794391][ T8480] ? nbp_backup_change (net/bridge/br_if.c:185 (discriminator 9))
[ 593.794565][ T8480] del_nbp (net/bridge/br_if.c:365)
[ 593.794701][ T8480] br_del_if (net/bridge/br_if.c:741)
[ 593.794880][ T8480] br_device_event (net/bridge/br.c:123)
[ 593.795146][ T8480] ? __pfx_br_device_event (net/bridge/br.c:29)
[ 593.795417][ T8480] ? packet_notifier (net/packet/af_packet.c:4282)
[ 593.795676][ T8480] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 593.795941][ T8480] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 593.796193][ T8480] unregister_netdevice_many_notify (net/core/dev.c:11571)
[ 593.796519][ T8480] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11512)
[ 593.796845][ T8480] ? rtnl_dellink (net/core/rtnetlink.c:3512)
[ 593.797107][ T8480] ? sock_def_readable (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/sock.c:3479)
[ 593.797374][ T8480] ? rtnl_is_locked (net/core/rtnetlink.c:164)
[ 593.797633][ T8480] ? unregister_netdevice_queue (net/core/dev.c:11497)
[ 593.797958][ T8480] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11496)
[ 593.798315][ T8480] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11496)
[ 593.798636][ T8480] rtnl_dellink (net/core/rtnetlink.c:3478 net/core/rtnetlink.c:3518)
[ 593.798903][ T8480] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3484)
[ 593.799188][ T8480] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 593.799445][ T8480] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 593.799693][ T8480] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6900)
[ 593.799952][ T8480] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 593.800220][ T8480] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 593.800480][ T8480] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6900)
[ 593.800738][ T8480] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3484)
[ 593.800997][ T8480] rtnetlink_rcv_msg (net/core/rtnetlink.c:6902)
[ 593.801232][ T8480] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6805)
[ 593.801445][ T8480] ? 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)
[ 593.801643][ T8480] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 593.801792][ T8480] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 593.801959][ T8480] netlink_rcv_skb (net/netlink/af_netlink.c:2543)
[ 593.802143][ T8480] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6805)
[ 593.802315][ T8480] ? __pfx_netlink_rcv_skb (net/netlink/af_netlink.c:2520)
[ 593.802481][ T8480] ? netlink_deliver_tap (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/netlink/af_netlink.c:340)
[ 593.802646][ T8480] ? 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)
[ 593.802824][ T8480] netlink_unicast (net/netlink/af_netlink.c:1322 net/netlink/af_netlink.c:1348)
[ 593.802998][ T8480] ? __pfx_netlink_unicast (net/netlink/af_netlink.c:1333)
[ 593.803162][ T8480] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 593.803325][ T8480] netlink_sendmsg (net/netlink/af_netlink.c:1892)
[ 593.803489][ T8480] ? __pfx_netlink_sendmsg (net/netlink/af_netlink.c:1811)
[ 593.803657][ T8480] ____sys_sendmsg (net/socket.c:711 net/socket.c:726 net/socket.c:2594)
[ 593.803833][ T8480] ? __pfx_____sys_sendmsg (net/socket.c:2540)
[ 593.803997][ T8480] ? __pfx_copy_msghdr_from_user (net/socket.c:2520)
[ 593.804213][ T8480] ___sys_sendmsg (net/socket.c:2650)
[ 593.804377][ T8480] ? __pfx____sys_sendmsg (net/socket.c:2637)
[ 593.804541][ T8480] ? kasan_save_stack (mm/kasan/common.c:49)
[ 593.804709][ T8480] ? kasan_save_stack (mm/kasan/common.c:48)
[ 593.804945][ T8480] ? __kasan_record_aux_stack (mm/kasan/generic.c:544)
[ 593.805202][ T8480] ? __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)
[ 593.805515][ T8480] ? __x64_sys_close (fs/open.c:1557 fs/open.c:1539 fs/open.c:1539)
[ 593.805719][ T8480] ? do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 593.805924][ T8480] ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 593.806150][ T8480] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 593.806329][ T8480] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 593.806505][ T8480] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 593.806686][ T8480] ? __virt_addr_valid (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:962 ./include/linux/mmzone.h:2058 arch/x86/mm/physaddr.c:65)
[ 593.806878][ T8480] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 593.807055][ T8480] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 593.807240][ T8480] __sys_sendmsg (net/socket.c:2680)
[ 593.807419][ T8480] ? __pfx___sys_sendmsg (net/socket.c:2665)
[ 593.807594][ T8480] ? __pfx_slab_free_after_rcu_debug (mm/slub.c:4643)
[ 593.807831][ T8480] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 593.808010][ T8480] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[  593.808231][ T8480] RIP: 0033:0x7f63f2d0a9a7
[ 593.808422][ T8480] 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)
[  593.809228][ T8480] RSP: 002b:00007ffdc05269b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[  593.809562][ T8480] RAX: ffffffffffffffda RBX: 00007ffdc05270f0 RCX: 00007f63f2d0a9a7
[  593.809824][ T8480] RDX: 0000000000000000 RSI: 00007ffdc0526a20 RDI: 0000000000000005
[  593.810083][ T8480] RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000078
[  593.810328][ T8480] R10: 00007f63f2bc84a8 R11: 0000000000000246 R12: 0000000000000001


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