The mlock() function shall cause those whole pages containing any part of the address space of the process starting at address addr and continuing for len bytes to be memory-resident until unlocked or until the process exits or execs another process image The implementation may require that addr be a multiple of {PAGESIZE} Upon successful return from mlock(), pages in the specified range shall be locked and memory-resident The appropriate privilege is required to lock process memory with mlock() Upon successful completion, the mlock() function shall return a value of zero Upon unsuccessful completion, no change is made to any locks in the address space of the process Upon unsuccessful completion, the function shall return a value of -1 The mlock() function shall set errno = ENOMEM if some or all of the address range specified by the addr and len arguments does not correspond to valid mapped pages in the address space of the process The mlock() function shall set errno = EAGAIN if some or all of the memory identified by the operation could not be locked when the call was made The mlock() function may set errno = EINVAL if the addr argument is not a multiple of {PAGESIZE} The mlock() function may set errno = ENOMEM if locking the pages mapped by the specified range would exceed an implementation-defined limit on the amount of memory that the process may lock The mlock() function may set errno = EPERM if the calling process does not have the appropriate privilege to perform the requested operation