Technique for tracking modification of content of regions of memory

Address translation circuitry (20) converts virtual addresses into physical addresses with reference to intermediate level and final level page tables. Final level descriptors within final level page tables identify address translation data for an associated region of memory. Intermediate level descriptors within intermediate level page tables identify intermediate address translation data used to identify an associated page table at a next level of the page tables. Page table update circuitry (35) maintains state information within each final and intermediate level descriptor, and updates the state information from a clean state to a dirty state: in the final level descriptors to indicate that a modification of content of the associated memory region is permitted; in the intermediate level descriptors to indicate occurrence of an update from the clean state to the dirty state within the state information of any final level descriptors that are accessed via that intermediate level descriptor.