I don't like it very much. You have two choices if a workload runsYou could allow the 'hugetlb zone' to shrink, allowing more kernel allocations. User pages at the boundary would be moved to make room.
out of the kernel allocatable pages. Either you spill into the reclaimable
zone or you fail the allocation. The first means that the huge pages
thing is unreliable, the second would mean that all the many problems
of limited lowmem would be back.
None of this is very attractive.