There have been a couple of bugzilla reports already about cases where a macvlan
or vlan is moved into another namespace. In these cases the parent device ifindex (iflink)
is no longer valid.


Normally it is not a big issue, until another device is created using the ifindex
of the parent

Does anyone have a suggested fix? Marking iflink as 0 won't work then the devices no
longer appear as slaves. Another possibility would be to make block creation of device
where ifindex matches existing iflink of other devices; but this would slow down device
creation.
 

The bugs come in as ip command bugs, but obviously the issue is in the kernel.

https://bugzilla.kernel.org/show_bug.cgi?id=66691
https://bugzilla.kernel.org/show_bug.cgi?id=75911