When does __netlink_insert return an error code -EBUSY?

[renmingshuai]

Recently, I encountered an issue that __netlink_insert() failed
and returned error code -EBUSY, which came from rhashtable_look-
up_insert_key(). I have not yet found the reason for returning
to -EBUSY. I noticed that in the 4e7c1330689e submission, -EBUSY
was changed to - ECOVERFLOW and returned to the user. Has anyone
encountered a similar problem? Can you please advise under what
circumstances __netlink_insert will return -EBUSY?