c = pageCache{
			base:  alignDown(addr, 64*pageSize),
			cache: ^chunk.pages64(chunkPageIndex(addr)),
			scav:  chunk.scavenged.block64(chunkPageIndex(addr)),
		}
	}

	// Set the page bits as allocated and clear the scavenged bits, but
	// be careful to only set and clear the relevant bits.
	cpi := chunkPageIndex(c.base)
	chunk.allocPages64(cpi, c.cache)

		// where it is, so mark it directly.
		i := chunkIndex(base)
		pi := chunkPageIndex(base)
		p.chunkOf(i).free1(pi)
		p.scav.index.free(i, pi, 1)
	} else {
		// Slow path: we're clearing more bits so we may need to iterate.
		sc, ec := chunkIndex(base), chunkIndex(limit)
		si, ei := chunkPageIndex(base), chunkPageIndex(limit)

		if sc == ec {
			// The range doesn't cross any chunk boundaries.

	ci, off := s.i.find(force)
	return ChunkIdx(ci), off
}

func (s *ScavengeIndex) AllocRange(base, limit uintptr) {
	sc, ec := chunkIndex(base), chunkIndex(limit-1)
	si, ei := chunkPageIndex(base), chunkPageIndex(limit-1)

	if sc == ec {
		// The range doesn't cross any chunk boundaries.
		s.i.alloc(sc, ei+1-si)
	} else {
		// The range crosses at least one chunk boundary.

	for i := start; i >= min; i-- {
		// Skip over chunks.
		if !s.chunks[i].load().shouldScavenge(gen, force) {
			continue
		}
		// We're still scavenging this chunk.
		if i == start {
			return i, chunkPageIndex(searchAddr)
		}
		// Try to reduce searchAddr to newSearchAddr.
		newSearchAddr := chunkBase(i) + pallocChunkBytes - pageSize
		if marked {
			// Attempt to be the first one to decrease the searchAddr