Metachunk pool uses an item pool to store Metachunk headers. The concept is simple, a growable "super-array" whose elements are address-stable and which has an built-in freelist.

This type of container is perfect for things like hash table entries or similar - small things with a long runtime. It reduces overhead over plain malloc and makes bulk-deletion of all items trivial.

It would be perfectly placed to serve as back buffer for the lookup table entries in NMTPreInit, provided the back buffer can use raw C-heap. Other possible future usages are as back buffer for the NMT malloc site table entries. So it would be nice to have this as generalized container.