When you have a mat that keeps migrating around the room or hooking your guests over, instead of an exorcism, try this carpet grip...

also good where carpets join in doorways,

I have made them in pairs,because they fix together with a joint.

my build plate is only 220mm, so 1 pair is only 400mm,not enough for a doorway, so you measure your doorway and scale another pair of the clamps to fit the excess. if you keep the width and the height the same you can adjust the length to suit. Only problem is this will slightly deform the holes but you were going to drill the floor so you can rebore the holes at the same time. they are 5mm dia.....