======================================
| [ 1253.293587][ T4450] #0: ffffffffb7de7a48 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink (net/core/rtnetlink.c:3521)
| [ 1253.293864][ T4450] #1: ffffffffb7dd6630 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [ 1253.294160][ T4450]
| [ 1253.294160][ T4450] stack backtrace:
[ 1253.294557][ T4450] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 1253.294746][ T4450] Call Trace:
[ 1253.294859][ T4450]  <TASK>
[ 1253.294936][ T4450] dump_stack_lvl (lib/dump_stack.c:123)
[ 1253.295089][ T4450] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 1253.295243][ T4450] validate_chain (kernel/locking/lockdep.c:3894)
[ 1253.295389][ T4450] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 1253.295537][ T4450] ? 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)
[ 1253.295685][ T4450] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 1253.295798][ T4450] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 1253.295956][ T4450] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 1253.296101][ T4450] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 1253.296283][ T4450] ? netconsole_process_cleanups_core (drivers/net/netconsole.c:242 (discriminator 11))
[ 1253.296469][ T4450] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 1253.296616][ T4450] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 1253.296762][ T4450] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 1253.296909][ T4450] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 1253.297099][ T4450] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 1253.297210][ T4450] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 1253.297390][ T4450] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 1253.297535][ T4450] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 1253.297683][ T4450] ? netconsole_netdev_event (drivers/net/netconsole.c:1082)
[ 1253.297830][ T4450] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 1253.297976][ T4450] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 1253.298129][ T4450] __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))
[ 1253.298278][ T4450] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 1253.298460][ T4450] ? __mutex_unlock_slowpath (./arch/x86/include/asm/atomic64_64.h:101 ./include/linux/atomic/atomic-arch-fallback.h:4329 ./include/linux/atomic/atomic-long.h:1506 ./include/linux/atomic/atomic-instrumented.h:4481 kernel/locking/mutex.c:913)
[ 1253.298605][ T4450] ? __pfx___mutex_unlock_slowpath (kernel/locking/mutex.c:890)
[ 1253.298786][ T4450] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 1253.298939][ T4450] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 1253.299091][ T4450] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 1253.299271][ T4450] ? netconsole_netdev_event (drivers/net/netconsole.c:1082)
[ 1253.299420][ T4450] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3189 kernel/locking/mutex.h:47 kernel/locking/mutex.c:66)
[ 1253.299568][ T4450] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 1253.299711][ T4450] ? netdev_master_upper_dev_get (net/core/dev.c:7230)
[ 1253.299893][ T4450] vrf_device_event (drivers/net/vrf.c:1110 drivers/net/vrf.c:1119 drivers/net/vrf.c:1804) vrf
[ 1253.300056][ T4450] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 1253.300217][ T4450] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 1253.300364][ T4450] unregister_netdevice_many_notify (net/core/dev.c:11575)
[ 1253.300545][ T4450] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 1253.300694][ T4450] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 1253.300846][ T4450] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11516)
[ 1253.301029][ T4450] ? 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)
[ 1253.301179][ T4450] ? mark_held_locks (kernel/locking/lockdep.c:4321)
[ 1253.301331][ T4450] ? __pfx_vlan_info_rcu_free (net/8021q/vlan_core.c:145)
[ 1253.301488][ T4450] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 1253.301672][ T4450] rtnl_dellink (net/core/rtnetlink.c:3487 net/core/rtnetlink.c:3527)
[ 1253.301823][ T4450] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3493)
[ 1253.301984][ T4450] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 1253.302136][ T4450] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 1253.302281][ T4450] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6909)
[ 1253.302433][ T4450] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 1253.302578][ T4450] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 1253.302727][ T4450] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6909)
[ 1253.302877][ T4450] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3493)
[ 1253.303025][ T4450] rtnetlink_rcv_msg (net/core/rtnetlink.c:6911)
[ 1253.303171][ T4450] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6814)
[ 1253.303317][ T4450] ? 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)
[ 1253.303469][ T4450] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 1253.303584][ T4450] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 1253.303737][ T4450] netlink_rcv_skb (net/netlink/af_netlink.c:2543)
[ 1253.303888][ T4450] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6814)
[ 1253.304033][ T4450] ? __pfx_netlink_rcv_skb (net/netlink/af_netlink.c:2520)
[ 1253.304183][ T4450] ? netlink_deliver_tap (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/netlink/af_netlink.c:340)
[ 1253.304334][ T4450] ? 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)
[ 1253.304488][ T4450] netlink_unicast (net/netlink/af_netlink.c:1322 net/netlink/af_netlink.c:1348)
[ 1253.304639][ T4450] ? __pfx_netlink_unicast (net/netlink/af_netlink.c:1333)
[ 1253.304788][ T4450] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 1253.304940][ T4450] netlink_sendmsg (net/netlink/af_netlink.c:1892)
[ 1253.305091][ T4450] ? __pfx_netlink_sendmsg (net/netlink/af_netlink.c:1811)
[ 1253.305240][ T4450] ____sys_sendmsg (net/socket.c:711 net/socket.c:726 net/socket.c:2594)
[ 1253.305390][ T4450] ? __pfx_____sys_sendmsg (net/socket.c:2540)
[ 1253.305541][ T4450] ? __pfx_copy_msghdr_from_user (net/socket.c:2520)
[ 1253.305728][ T4450] ___sys_sendmsg (net/socket.c:2650)
[ 1253.305880][ T4450] ? __pfx____sys_sendmsg (net/socket.c:2637)
[ 1253.306029][ T4450] ? kasan_save_stack (mm/kasan/common.c:49)
[ 1253.306175][ T4450] ? kasan_save_stack (mm/kasan/common.c:48)
[ 1253.306322][ T4450] ? __kasan_record_aux_stack (mm/kasan/generic.c:544)
[ 1253.306470][ T4450] ? __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)
[ 1253.306664][ T4450] ? __x64_sys_close (fs/open.c:1557 fs/open.c:1539 fs/open.c:1539)
[ 1253.306816][ T4450] ? do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 1253.306967][ T4450] ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 1253.307152][ T4450] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 1253.307303][ T4450] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 1253.307454][ T4450] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 1253.307601][ T4450] ? __virt_addr_valid (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:962 ./include/linux/mmzone.h:2058 arch/x86/mm/physaddr.c:65)
[ 1253.307750][ T4450] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 1253.307908][ T4450] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 1253.308057][ T4450] __sys_sendmsg (net/socket.c:2680)
[ 1253.308208][ T4450] ? __pfx___sys_sendmsg (net/socket.c:2665)
[ 1253.308356][ T4450] ? __pfx_slab_free_after_rcu_debug (mm/slub.c:4643)
[ 1253.308548][ T4450] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 1253.308695][ T4450] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 1253.308885][ T4450] RIP: 0033:0x7f0ee96219a7
[ 1253.309050][ T4450] 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)
[ 1253.309564][ T4450] RSP: 002b:00007ffda29fcc38 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 1253.309791][ T4450] RAX: ffffffffffffffda RBX: 00007ffda29fd360 RCX: 00007f0ee96219a7
[ 1253.310023][ T4450] RDX: 0000000000000000 RSI: 00007ffda29fcca0 RDI: 0000000000000005
[ 1253.310249][ T4450] RBP: 0000000000000002 R08: 0000000000000003 R09: 0000000000000078
[ 1253.310469][ T4450] R10: 00007f0ee94dfef8 R11: 0000000000000246 R12: 0000000000000002


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