A patroll is one or more (hard to tell numbers) of trolls that are not seeking controll of a large public wiki or other public space, but do seek to detect and oppose any impediments to trolling. It is a nonviolent patrol that is usually composed of wise citizens:
For example, in Norway where many trolls live and are accepted as part of the community, blocked roads that provide access to areas where the government does not want the public seeing what is going on, might be unblocked by a patroll. Local villagers when asked will say "the trolls did it". This is considered an acceptable official answer in Norway, since such incidents are rarely or never investigated.
In Toronto, Canada which has a quasi-official Troll Protocol, the function of a TorontoTroll is to criticize public buildings and spaces. For instance, complaining that they do not permit disabled trolls inside to complain about the lack of access or other problems the trolls are in a unique position to see.
In neither of these cases do the trolls seek controll and certainly not control of the space - to patroll is not to occupy or inhabit. While a patroll may visit spaces like those under a bridge, unless they set up a sort of informal camp there, they do not controll such spaces. And if they do not defend it with violence, or they are not in control of it. Likewise they are not a patrol, as they do not use violence to get their objectives. The additional 'l' is as in 'lullaby' or 'lovingly'.