======================================
| [ 349.937379][ T4904] #6: ffffffffa5607e88 (rtnl_mutex){+.+.}-{4:4}, at: nsim_create (drivers/net/netdevsim/netdev.c:686 drivers/net/netdevsim/netdev.c:731 drivers/net/netdevsim/netdev.c:802) netdevsim
| [ 349.937711][ T4904] #7: ffffffffa55f6a70 ((netdev_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
| [  349.938073][ T4904]
| [  349.938073][ T4904] stack backtrace:
[  349.938559][ T4904] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  349.938799][ T4904] Call Trace:
[  349.938939][ T4904]  <TASK>
[ 349.939036][ T4904] dump_stack_lvl (lib/dump_stack.c:123)
[ 349.939220][ T4904] print_deadlock_bug (kernel/locking/lockdep.c:3040)
[ 349.939401][ T4904] validate_chain (kernel/locking/lockdep.c:3894)
[ 349.939583][ T4904] ? __pfx_validate_chain (kernel/locking/lockdep.c:3860)
[ 349.939763][ T4904] ? 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)
[ 349.939939][ T4904] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 349.940075][ T4904] __lock_acquire (kernel/locking/lockdep.c:5226)
[ 349.940278][ T4904] ? udp_tunnel_nic_netdevice_event (net/ipv4/udp_tunnel_nic.c:909)
[ 349.940504][ T4904] ? really_probe (drivers/base/dd.c:579 drivers/base/dd.c:658)
[ 349.940683][ T4904] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851)
[ 349.940859][ T4904] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 349.941086][ T4904] ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[ 349.941308][ T4904] ? find_held_lock (kernel/locking/lockdep.c:5339)
[ 349.941485][ T4904] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 349.941670][ T4904] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 37))
[ 349.941850][ T4904] ? lock_acquire (kernel/locking/lockdep.c:5822)
[ 349.942029][ T4904] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 349.942252][ T4904] down_read (./arch/x86/include/asm/preempt.h:79 kernel/locking/rwsem.c:1246 kernel/locking/rwsem.c:1261 kernel/locking/rwsem.c:1526)
[ 349.942391][ T4904] ? blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 349.942613][ T4904] ? __pfx_down_read (kernel/locking/rwsem.c:1522)
[ 349.942795][ T4904] ? notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 349.942983][ T4904] blocking_notifier_call_chain (kernel/notifier.c:380 kernel/notifier.c:368)
[ 349.943164][ T4904] call_netdevice_notifiers (net/core/dev.c:2062)
[ 349.943345][ T4904] ? __pfx_call_netdevice_notifiers (net/core/dev.c:2062)
[ 349.943567][ T4904] ? 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)
[ 349.943749][ T4904] udp_tunnel_nic_register (./include/net/udp_tunnel.h:138 net/ipv4/udp_tunnel_nic.c:825)
[ 349.943937][ T4904] udp_tunnel_nic_netdevice_event (net/ipv4/udp_tunnel_nic.c:893)
[ 349.944157][ T4904] notifier_call_chain (kernel/notifier.c:85 (discriminator 2))
[ 349.944351][ T4904] blocking_notifier_call_chain (kernel/notifier.c:381 kernel/notifier.c:368)
[ 349.944531][ T4904] register_netdevice (./include/linux/notifier.h:207 net/core/dev.c:10676)
[ 349.944711][ T4904] ? __pfx_register_netdevice (net/core/dev.c:10532)
[ 349.944892][ T4904] nsim_create (drivers/net/netdevsim/netdev.c:742 drivers/net/netdevsim/netdev.c:802) netdevsim
[ 349.945085][ T4904] __nsim_dev_port_add (drivers/net/netdevsim/dev.c:1393) netdevsim
[ 349.945319][ T4904] ? mark_lock (kernel/locking/lockdep.c:4727 (discriminator 3))
[ 349.945461][ T4904] ? __pfx___nsim_dev_port_add (drivers/net/netdevsim/dev.c:1357) netdevsim
[ 349.945693][ T4904] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
[ 349.945919][ T4904] nsim_dev_port_add_all (drivers/net/netdevsim/dev.c:1449) netdevsim
[ 349.946152][ T4904] nsim_drv_probe (drivers/net/netdevsim/dev.c:1607) netdevsim
[ 349.946339][ T4904] ? __pfx_nsim_drv_probe (drivers/net/netdevsim/dev.c:1528) netdevsim
[ 349.946572][ T4904] ? kernfs_create_link (fs/kernfs/symlink.c:48)
[ 349.946759][ T4904] ? kernfs_put (./arch/x86/include/asm/atomic.h:67 (discriminator 1) ./include/linux/atomic/atomic-arch-fallback.h:2278 (discriminator 1) ./include/linux/atomic/atomic-instrumented.h:1384 (discriminator 1) fs/kernfs/dir.c:557 (discriminator 1))
[ 349.946897][ T4904] ? sysfs_do_create_link_sd (fs/sysfs/symlink.c:48)
[ 349.947077][ T4904] really_probe (drivers/base/dd.c:579 drivers/base/dd.c:658)
[ 349.947256][ T4904] __driver_probe_device (drivers/base/dd.c:800)
[ 349.947436][ T4904] driver_probe_device (drivers/base/dd.c:830)
[ 349.947614][ T4904] __device_attach_driver (drivers/base/dd.c:959)
[ 349.947793][ T4904] ? __pfx___device_attach_driver (drivers/base/dd.c:922)
[ 349.948018][ T4904] bus_for_each_drv (drivers/base/bus.c:459)
[ 349.948203][ T4904] ? __pfx_bus_for_each_drv (drivers/base/bus.c:447)
[ 349.948382][ T4904] ? bus_to_subsys (drivers/base/bus.c:85)
[ 349.948559][ T4904] ? __pfx___lock_release (kernel/locking/lockdep.c:5501)
[ 349.948738][ T4904] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5814)
[ 349.948919][ T4904] __device_attach (drivers/base/dd.c:1030)
[ 349.949103][ T4904] ? __pfx___device_attach (drivers/base/dd.c:1001)
[ 349.949287][ T4904] ? bus_to_subsys (drivers/base/bus.c:85)
[ 349.949467][ T4904] ? do_raw_spin_unlock (./arch/x86/include/asm/atomic.h:23 ./include/linux/atomic/atomic-arch-fallback.h:457 ./include/linux/atomic/atomic-instrumented.h:33 ./include/asm-generic/qspinlock.h:57 kernel/locking/spinlock_debug.c:101 kernel/locking/spinlock_debug.c:141)
[ 349.949648][ T4904] bus_probe_device (drivers/base/bus.c:534)
[ 349.949827][ T4904] device_add (drivers/base/core.c:3672)
[ 349.950005][ T4904] ? __pfx_device_add (drivers/base/core.c:3548)
[ 349.950184][ T4904] ? __init_waitqueue_head (./include/linux/list.h:37 kernel/sched/wait.c:12)
[ 349.950366][ T4904] new_device_store (drivers/net/netdevsim/bus.c:443 drivers/net/netdevsim/bus.c:173) netdevsim
[ 349.950599][ T4904] ? __pfx_new_device_store (drivers/net/netdevsim/bus.c:142) netdevsim
[ 349.950835][ T4904] ? __pfx_sysfs_kf_write (fs/sysfs/file.c:132)
[ 349.951016][ T4904] ? sysfs_file_ops (fs/sysfs/file.c:31 (discriminator 1))
[ 349.951197][ T4904] ? __pfx_sysfs_kf_write (fs/sysfs/file.c:132)
[ 349.951375][ T4904] kernfs_fop_write_iter (fs/kernfs/file.c:334)
[ 349.951553][ T4904] vfs_write (fs/read_write.c:586 fs/read_write.c:679)
[ 349.951698][ T4904] ? __pfx_vfs_write (fs/read_write.c:660)
[ 349.951877][ T4904] ? __lock_release (kernel/locking/lockdep.c:5525)
[ 349.952065][ T4904] ? do_user_addr_fault (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 ./include/linux/mm.h:742 arch/x86/mm/fault.c:1340)
[ 349.952247][ T4904] ? __pfx___up_read (kernel/locking/rwsem.c:1337)
[ 349.952428][ T4904] ksys_write (fs/read_write.c:731)
[ 349.952563][ T4904] ? __pfx_ksys_write (fs/read_write.c:721)
[ 349.952742][ T4904] ? do_user_addr_fault (./include/linux/rcupdate.h:882 ./include/linux/mm.h:742 arch/x86/mm/fault.c:1340)
[ 349.952923][ T4904] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
[ 349.953105][ T4904] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[  349.953333][ T4904] RIP: 0033:0x7fa63adcbb77
[ 349.953520][ T4904] Code: 0b 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
All code
========
   0:	0b 00                	or     (%rax),%eax
   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 b7                	jmp    0xffffffffffffffc7
  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 01 00 00 00       	mov    $0x1,%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:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  3c:	48                   	rex.W
  3d:	89                   	.byte 0x89
  3e:	74 24                	je     0x64

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:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
  12:	48                   	rex.W
  13:	89                   	.byte 0x89
  14:	74 24                	je     0x3a
[  349.954149][ T4904] RSP: 002b:00007ffd33b20018 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  349.954434][ T4904] RAX: ffffffffffffffda RBX: 00007fa63abb1140 RCX: 00007fa63adcbb77
[  349.954707][ T4904] RDX: 0000000000000009 RSI: 00005561b46e06c0 RDI: 0000000000000006
[  349.954973][ T4904] RBP: 0000000000000009 R08: 0000000000000000 R09: 0000000000000000
[  349.955241][ T4904] R10: 0000000000000002 R11: 0000000000000246 R12: 00007fa62cc69c40


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