Was the famine in II Kings 8:1 the same famine as in Samaria in II Kings 6:24-31? Did the famine in II Kings 8:1 include all the land of Israel?
The first few chapters of II Kings are a bit difficult to place into a timeline because often the name of the current king is not mentioned. For example, while we know that it was Ben-Hadad who besieged Samaria in II Kings 6-7, the name of the king of Israel is not mentioned. Most likely it was Joram, son of Ahab. The wound that leads to his death is mentioned in II Kings 8:28-29 and he is killed by an arrow shot by Jehu in II Kings 9:24.
The event, related at the beginning of chapter 8, explains how the Shunammite woman ended up bringing a petition to the king of Israel. She was warned that there would be a seven-year famine in the land, so she left with her family to dwell in the land of the Philistines. At the end of the seven years, she returned, but during the time she lost control over her land. She just happened to come before the king while Elisha's servant was telling the king about how Elisha had restored to life a child of a Shunammite woman. It is implied that this is more than just mere coincidence. The king restored her lands and all back payments.
Thus her leaving Israel had happened seven years prior, so it is likely the severe famine mentioned in II Kings 6 is the same famine. There isn't enough time in Joram and Ben-Hadad's reigns to allow for two sequential famines when one lasted seven years.
Most of these events are taking place around the valley of Jezreel. This valley was Israel's primary farmland, so drought here would affect all of Israel. The fact that the Shunammite woman went all the way into the land of the Philistines from the valley of Jezreel does indicate that it was an extensive famine.