The books are right - though the actual effect on the pilot may vary: on the way up, if your passages are blocked, you get what is called a 'reverse block' in scuba parlance (this can be horrendously painful -I once had one on a 5 hour flight from the Middle East - 5 hours of agony until decent into Heathrow) - and there is no relief method other than to descend - but if the blockage is only partial, then your passages may equalise enough for you to feel nothing.
If you have a blockage on descent, and this is the most common form, then it can be relieved by the old scuba methods of either holding your nostrils shut with your fingers, closing the mouth, and blowing gently against them - (blow too hard and you will damage things). If the blockage is partial, it may clear itself sufficiently on the way down that the symptoms either stabilise or disappear entirely, despite coming on down.
PS the other method on the way down is to open your mouth and work the jaw, yawning if possible - a lot of scuba divers (myself included) use this method exclusively - and bear in mind on a dive you ALWAYS get enough pressure increase to necessitate some clearing.