I hang wallpaper for a living and run into this problem after removing paper all the time. Sometimes they're big tares and sometimes small. But, before you paper over torn drywall or wallboard you have to putting over the areas with drywall mud. The smaller the tare the thinner this needs applied. Let dry, sand and smooth. Then prime over it with wallsizing ( KILT primer) Then you can paper. If you dont mud over the tares anything you put on top , like, paint or even sizing or primer, it will only bubble like wet paper. GOODLUCK !