// level of p.summary into page-aligned addresses which cover that
	// range of indices.
	summaryRangeToSumAddrRange := func(level, sumIdxBase, sumIdxLimit int) addrRange {
		baseOffset := alignDown(uintptr(sumIdxBase)*pallocSumBytes, physPageSize)
		limitOffset := alignUp(uintptr(sumIdxLimit)*pallocSumBytes, physPageSize)
		base := unsafe.Pointer(&p.summary[level][0])
		return addrRange{

func sysHugePageOS(v unsafe.Pointer, n uintptr) {
	if physHugePageSize != 0 {
		// Round v up to a huge page boundary.
		beg := alignUp(uintptr(v), physHugePageSize)
		// Round v+n down to a huge page boundary.
		end := alignDown(uintptr(v)+n, physHugePageSize)

		if beg < end {
			madvise(unsafe.Pointer(beg), end-beg, _MADV_HUGEPAGE)
		}
	}
}

func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {