Linda,
Malleletry is also spelled Mullaletragh. Griffiths Valuation for 1864 lists a Thomas Cartmill in that townland. He had plot 20 which was a house and a total of just over 14 acres (in 2 separate pieces of land). So, assuming it’s the right family, he was able to do some farming as well as masonry work. His landlord was Louisa Bacon.
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=nameSearch
The revaluation records show the property remaining in Thomas’s name until 1887 when it changes to Lydia (his widow perhaps) and then in 1892 to another Thomas. It remains in that Thomas’s name until 1929 when that series of records stops. He purchased outright ownership of the property in 1922 under the Land Act. (A scheme which gave government mortgages to enable farmers buy their land).
https://www.nidirect.gov.uk/proni
Household in 1901:
http://www.census.nationalarchives.ie/pages/1901/Armagh/Richhill/Mullaletragh/1018910/
and in 1911:
http://www.census.nationalarchives.ie/pages/1911/Armagh/Rich_Hill/Mullaletragh/330409/
Probate abstract (full will held in paper format in PRONI):
Cartmell Thomas of Mullaletragh county Armagh farmer died 18 April 1934 Probate Belfast 4 February to William John Lamb and Isaac Lamb farmers. Effects £63 5s.
There’s a death for a Thos Cartwell, registered in Armagh 3.1.1886 aged 76. That might be the first Thomas’s death. You can view the original certificates on-line on the GRONI website, using the “search registrations” option:
https://geni.nidirect.gov.uk
You will need to open an account and buy some credits. It costs £2.50 (sterling) to a view a certificate.
The tithe applotment records for 1833 show a David Cartmill farming in the townland then.
http://www.irishgenealogyhub.com/armagh/tithe-applotments/kilmore-parish.php#.VwYZAqt9eg0
It’s not a big townland and this is the only Cartmill household that appears in it’s records so presumably it must be part of your family. The farm today is on the Tullygarden Rd, just west of Portadown. You probably need to go through Kilmore Church of Ireland parish records to work out how all these people are connected.
Looking at Ballyleny in Griffiths, the only McMahon household was that of an Alexander who had a weaver’s cottage. It was plot 3e and was on Thomas Walker’s farm. You can use the revaluation records to see how long he lived there, and then search for his death certificate.