+ /* Note that we usually try to avoid adjacent free blocks */
+ /* that are either both mapped or both unmapped. But that */
+ /* isn't guaranteed to hold since we remap blocks when we */
+ /* split them, and don't merge at that point. It may also */
+ /* not hold if the merged block would be too big. */
+ if (IS_MAPPED(hhdr) && !IS_MAPPED(nexthdr)) {