Golang字节数组到C#，.NetCore，如何释放非托管内存的不安全ptr

我现在从C#p/Invoke中的go with C.CBytes读取字节数组

C#

戈兰

//export GetData
func GetData() unsafe.Pointer {
    //read bytes to data, data is byte[]
    buf := new(bytes.Buffer)
    if data == nil {
        writeInt32(buf, int32(0))
    }else {
        writeInt32(buf, int32(len(data)))
        binary.Write(buf, binary.LittleEndian, data)
    }
    cData := C.CBytes(buf.Bytes())
    return cData
 }

//export Free
func Free(ptr unsafe.Pointer){
    if ptr != nil{
        log.Println("Free c memory", ptr)
        C.free(ptr)
    }
}

我发现非托管内存没有释放，所以我在go中添加了一个Free func，并在C中调用它#

戈兰

//export GetData
func GetData() unsafe.Pointer {
    //read bytes to data, data is byte[]
    buf := new(bytes.Buffer)
    if data == nil {
        writeInt32(buf, int32(0))
    }else {
        writeInt32(buf, int32(len(data)))
        binary.Write(buf, binary.LittleEndian, data)
    }
    cData := C.CBytes(buf.Bytes())
    return cData
 }

//export Free
func Free(ptr unsafe.Pointer){
    if ptr != nil{
        log.Println("Free c memory", ptr)
        C.free(ptr)
    }
}

C#

但结果是非托管内存仍然被占用

这里有什么问题？我用错了吗