Please be aware that the article describes a problem with a specific implementation of THP. Other operating systems implement it differently and don't suffer from the same caveats (though any implementation will of course have its own disadvantages, since THP support requires making various tradeoffs and policy decisions). FreeBSD's implementation (based on [1]) is more conservative and works by opportunistically reserving physically contiguous ranges of memory in a way that allows THP promotion if the application (or kernel) actually makes use of all the pages backed by the large mapping. It's tied in to the page allocator in a way that avoids the "leaks" described in the article, and doesn't make use of expensive scans. Moreover, the reservation system enables other optimizations in the memory management subsystem.

[1] https://www.cs.rice.edu/~druschel/publications/superpages.pd...