Panic loading linsysfs with INVARIANTS configured

On a server class ARM (Ampere) running an up to date stable/13 kernel with INVARIANTS I get a panic in VFS code if I kldload linsysfs:

pfs_add_node: homonymous siblings

Anybody else see this recently?

On a Raspberry Pi 3B with INVARIANTS the kldload works.

There is a comment before the panic code
 	/* XXX no locking! */
which makes me wonder if 32 cores is too many for this code.

(Related to this: Does anybody get crash dumps on an Ampere system?  If I configure DDB and use the debugger crash dump command it hangs after the 1% progress line.  Without the debugger the system just hangs without printing any progress, but at least I can see the panic message before I power cycle it.)