1. A method of sharing memory pages in a virtualized system comprising a first virtual machine (VM) and a corresponding first virtual machine monitor (VMM), the method comprising: the first VMM maintaining a first mapping of a first guest physical page (GPPN) to a first machine page entry (VMPN) backed by a first machine memory page (MPN); the first VMM maintaining a second mapping of a second guest physical page (GPPN) to a second machine page entry (VMPN) backed by a second machine memory page (MPN); the first VMM accessing content of the first and second MPNs and determining whether or not the content of the first and second MPNs can each be represented by a first non-zero regular expression (RE); and if the content of the first and second MPNs can be represented by the first RE, then the first VMM re-mapping the first and second GPPNs to a same VMPN, wherein the first and second GPPNs are sharing the same MPN within the first VM, wherein determining if the content of the first and second MPNs represents a regular expression comprises evaluating a subset of the content of the MPN to determine whether the content might be a regular expression.