In Game of Thrones season 7 episode 6, Benjen Stark (Coldhands in the books) shows up to save Jon's life after he misses the dragon-bus to school. He is then quickly overpowered by hundreds of wights because he brought a censer to a mace fight.
In season 6 of Game of Thrones, however, it was revealed that Benjen was rescued from a lethal stomach piercing by the children of the forest -- by inserting a shard of dragonglass into his chest. This was previously shown to be the way the Children also created the White Walkers.
The White Walkers have been shown to be impervious to injury by conventional means -- only Valyrian steel and dragonglass have been shown to have any effect. As Benjen was subjected to the White Walker treatment, is he similarly granted resistance to conventional weaponry -- and thus effective immunity to the damage inflicted by the dead man dogpile?