A method for managing memory using a virtual memory manager includes receiving a memory allocation request, allocating memory of a physical address space in response to the memory allocation request, mapping an address value of the memory allocated in the physical address space to consecutive primary virtual address space, and mapping the address value of the primary virtual address space to one of a first and second secondary virtual address spaces to process a new memory allocation request in a situation where memory a fragmentation occurs. Other embodiments are also disclosed. The methods and apparatuses of the present disclosure are capable of moving active memory blocks of the fragmented virtual memory space to another virtual memory space to resolve the memory fragmentation even when a memory fragmentation occurs.