Having read hundreds of posts on the whirlpool ausiie cx-5 forum, they reported getting rising oil on the early cars regaurdless of how the car was run.
In particular one chap with the problem spent most of his time on motorways.
I understand Mazda do a regen depending on miles regardless of the soot content, that timed regen period has been lengthened by a software update, they was also a batch of faulty sensors that had to be replaced.
There's no need to do any thrash down the motorway or anywhere else, just avoid excessive stop start city driving, petrol or diesel cars don't like that treatment. If you do get a DPF dash light on drive it over 1500rpm for 15 to 20mins until the light goes off.
I only do 7K miles a year, mainly short journeys, and I'm on my second DPF car, first one was an 2009 Xtrail, and I have NEVER had a DPF light up on the dash. So that's around 6 years driving with DPF.
I do get around 8mm oil rise with my Mazda, over a year but I don't see it as a problem with 7K oil changes.
I've recently had a remap and oil change end of July and the oil level is just over the full mark, so perhaps the last remap has improved things.