// the first free page the slow way.
		addr, _ := p.find(1)
		if addr == 0 {
			// We failed to find adequate free space, so mark the searchAddr as OoM
			// and return an empty pageCache.
			p.searchAddr = maxSearchAddr()
			return pageCache{}
		}
		ci = chunkIndex(addr)
		chunk = p.chunkOf(ci)
		c = pageCache{
			base:  alignDown(addr, 64*pageSize),
			cache: ^chunk.pages64(chunkPageIndex(addr)),