Technologies are generally described for systems, devices and methods effective to generate an alert in a computing system. In some examples, a read request may be identified to read from a memory location in a memory. The memory location may include first data accessible by a virtual machine and an instance manager module. The first data may be allowed to be read from the memory location. A write request may be identified to write second data to the memory location. A flag may be identified in response to the identification of the write request. The flag may be associated with the memory location. An alert may be generated, based on the identification of the flag and the identification of the write request.