======================================
| [ 920.686744][ T7961] #0: ffffffffb7407e88 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink (net/core/rtnetlink.c:3521)
| [ 920.687012][ T7961] #1: ffffffffb73f6a70 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [  920.687311][ T7961]
| [  920.687311][ T7961] stack backtrace:
[  920.687716][ T7961] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  920.687904][ T7961] Call Trace:
[  920.688018][ T7961]  <TASK>
[ 920.688095][ T7961] dump_stack_lvl (lib/dump_stack.c:123)
[ 920.688250][ T7961] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 920.688403][ T7961] validate_chain (kernel/locking/lockdep.c:3894)
[ 920.688554][ T7961] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 920.688706][ T7961] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 920.688855][ T7961] ? 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)
[ 920.689008][ T7961] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 920.689124][ T7961] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 920.689283][ T7961] ? acpi_ns_build_internal_name (drivers/acpi/acpica/nsutils.c:233 (discriminator 3))
[ 920.689473][ T7961] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 920.689622][ T7961] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 920.689812][ T7961] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 920.689963][ T7961] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 920.690112][ T7961] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 920.690260][ T7961] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 920.690446][ T7961] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 920.690563][ T7961] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 920.690753][ T7961] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 920.690905][ T7961] ? __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)
[ 920.691056][ T7961] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 920.691207][ T7961] __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))
[ 920.691360][ T7961] ? __pfx___netdev_upper_dev_unlink (net/core/dev.c:8151)
[ 920.691549][ T7961] ? synchronize_rcu_expedited (kernel/rcu/tree_exp.h:995 (discriminator 1))
[ 920.691737][ T7961] ? __pfx_autoremove_wake_function (kernel/sched/wait.c:383)
[ 920.691925][ T7961] netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 920.692074][ T7961] ? __pfx_netdev_upper_dev_unlink (net/core/dev.c:8190)
[ 920.692258][ T7961] ? 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)
[ 920.692406][ T7961] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 920.692557][ T7961] ? netdev_master_upper_dev_get (net/core/dev.c:7230)
[ 920.692749][ T7961] ovs_netdev_detach_dev (net/openvswitch/vport-netdev.c:158 (discriminator 11)) openvswitch
[ 920.692952][ T7961] ? ovs_netdev_get_vport (net/openvswitch/vport-netdev.c:196 (discriminator 3)) openvswitch
[ 920.693156][ T7961] dp_device_event (net/openvswitch/dp_notify.c:77) openvswitch
[ 920.693355][ T7961] ? trace_notifier_run (./include/trace/events/notifier.h:59 (discriminator 37))
[ 920.693505][ T7961] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 920.693655][ T7961] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 920.693807][ T7961] unregister_netdevice_many_notify (net/core/dev.c:11575)
[ 920.694003][ T7961] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11516)
[ 920.694188][ T7961] ? rtnl_dellink (net/core/rtnetlink.c:3521)
[ 920.694336][ T7961] ? sock_def_readable (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/sock.c:3479)
[ 920.694490][ T7961] ? rtnl_is_locked (net/core/rtnetlink.c:163)
[ 920.694640][ T7961] ? unregister_netdevice_queue (net/core/dev.c:11501)
[ 920.694825][ T7961] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11500)
[ 920.695012][ T7961] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11500)
[ 920.695201][ T7961] rtnl_dellink (net/core/rtnetlink.c:3487 net/core/rtnetlink.c:3527)
[ 920.695351][ T7961] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3493)
[ 920.695517][ T7961] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 920.695667][ T7961] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 920.695832][ T7961] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6909)
[ 920.696001][ T7961] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 920.696165][ T7961] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 920.696329][ T7961] ? rtnetlink_rcv_msg (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/core/rtnetlink.c:6909)
[ 920.696494][ T7961] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3493)
[ 920.696662][ T7961] rtnetlink_rcv_msg (net/core/rtnetlink.c:6911)
[ 920.696821][ T7961] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6814)
[ 920.696970][ T7961] ? 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)
[ 920.697119][ T7961] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 920.697233][ T7961] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 920.697381][ T7961] netlink_rcv_skb (net/netlink/af_netlink.c:2543)
[ 920.697529][ T7961] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6814)
[ 920.697684][ T7961] ? __pfx_netlink_rcv_skb (net/netlink/af_netlink.c:2520)
[ 920.697836][ T7961] ? netlink_deliver_tap (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 net/netlink/af_netlink.c:340)
[ 920.697986][ T7961] ? 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)
[ 920.698135][ T7961] netlink_unicast (net/netlink/af_netlink.c:1322 net/netlink/af_netlink.c:1348)
[ 920.698286][ T7961] ? __pfx_netlink_unicast (net/netlink/af_netlink.c:1333)
[ 920.698436][ T7961] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 920.698584][ T7961] netlink_sendmsg (net/netlink/af_netlink.c:1892)
[ 920.698739][ T7961] ? __pfx_netlink_sendmsg (net/netlink/af_netlink.c:1811)
[ 920.698890][ T7961] ____sys_sendmsg (net/socket.c:711 net/socket.c:726 net/socket.c:2594)
[ 920.699041][ T7961] ? __pfx_____sys_sendmsg (net/socket.c:2540)
[ 920.699188][ T7961] ? __pfx_copy_msghdr_from_user (net/socket.c:2520)
[ 920.699384][ T7961] ___sys_sendmsg (net/socket.c:2650)
[ 920.699533][ T7961] ? __pfx____sys_sendmsg (net/socket.c:2637)
[ 920.699681][ T7961] ? kasan_save_stack (mm/kasan/common.c:49)
[ 920.699833][ T7961] ? kasan_save_stack (mm/kasan/common.c:48)
[ 920.699982][ T7961] ? __kasan_record_aux_stack (mm/kasan/generic.c:544)
[ 920.700133][ T7961] ? __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)
[ 920.700319][ T7961] ? __x64_sys_close (fs/open.c:1557 fs/open.c:1539 fs/open.c:1539)
[ 920.700469][ T7961] ? do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 920.700619][ T7961] ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 920.700806][ T7961] ? __lock_acquire (kernel/locking/lockdep.c:5226)
[ 920.700955][ T7961] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 920.701109][ T7961] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 920.701260][ T7961] ? __virt_addr_valid (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:962 ./include/linux/mmzone.h:2058 arch/x86/mm/physaddr.c:65)
[ 920.701413][ T7961] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 920.701562][ T7961] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 920.701713][ T7961] __sys_sendmsg (net/socket.c:2680)
[ 920.701864][ T7961] ? __pfx___sys_sendmsg (net/socket.c:2665)
[ 920.702013][ T7961] ? __pfx_slab_free_after_rcu_debug (mm/slub.c:4643)
[ 920.702208][ T7961] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 920.702359][ T7961] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[  920.702545][ T7961] RIP: 0033:0x7fd5adb3a9a7
[ 920.702704][ T7961] 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)
[  920.703234][ T7961] RSP: 002b:00007ffec51ff7b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[  920.703457][ T7961] RAX: ffffffffffffffda RBX: 00007ffec51ffee0 RCX: 00007fd5adb3a9a7
[  920.703680][ T7961] RDX: 0000000000000000 RSI: 00007ffec51ff820 RDI: 0000000000000005
[  920.703902][ T7961] RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000078
[  920.704128][ T7961] R10: 00007fd5ad9f8ef8 R11: 0000000000000246 R12: 0000000000000001


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