base:   250,
			expect: 50,
			ranges: large,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			a := MakeAddrRanges(test.ranges...)
			i := a.FindSucc(test.base)
			if i != test.expect {
				t.Fatalf("expected %d, got %d", test.expect, i)
			}
		})
	}

	// any existing range.
	//
	// This will be used to look at what memory in the summary array is already
	// mapped before and after this new range.
	inUseIndex := p.inUse.findSucc(base)

	// Walk up the radix tree and map summaries in as needed.
	for l := range p.summary {
		// Figure out what part of the summary array this new address space needs.