A method and module for performing a crash dump in a data processing apparatus in which memory for running the crash dump routine is allocated at the time of the crash. The method comprises running a first routine to identify memory locations of data for use by a second routine; allocating memory for performing the second routine from a memory range that does not contain the identified memory locations; and running the second routine using the allocated memory, wherein the first routine comprises a dummy crash dump routine and the second routine comprises a crash dump routine. The dummy crash dump may use smaller data sizes and does not perform any input or output to non-volatile storage of the data to be dumped. When a memory range that is safe to be reused has been identified, the data stored therein can be dumped and then memory for performing the actual crash dump routine can be allocated from the memory range and be reused for performing the actual crash dump routine.