_ammAllocatePrt took pool pages one at a time and mapped and recorded them run by run, so a failure on run k lost the pool pages of runs k to n. It now maps the unbacked part through AmmPool::MapScattered and returns the range to the reservation if that throws, and the unused _takePoolPages is gone.
Fail each allocation of a map from a fragmented pool, a map whose host call fails after each run, and a page insertion, and check that the pool and the page records are unchanged after every failure and that a map of one page more than the pool holds is still refused.
Dean Galvin