}
			if h.arenasHugePages {
				sysHugePage(unsafe.Pointer(l2), unsafe.Sizeof(*l2))
			} else {
				sysNoHugePage(unsafe.Pointer(l2), unsafe.Sizeof(*l2))
			}
			atomic.StorepNoWB(unsafe.Pointer(&h.arenas[ri.l1()]), unsafe.Pointer(l2))
		}

		if l2[ri.l2()] != nil {
			throw("arena already initialized")
		}
		var r *heapArena

	p := fresh.tryAlloc(bytesNeeded)
	if p == nil {
		throw("markBits overflow")
	}

	// Add the fresh arena to the "next" list.
	fresh.next = gcBitsArenas.next
	atomic.StorepNoWB(unsafe.Pointer(&gcBitsArenas.next), unsafe.Pointer(fresh))

	unlock(&gcBitsArenas.lock)
	return p
}

// newAllocBits returns a pointer to 8 byte aligned bytes
// to be used for this span's alloc bits.