The last posting asking about previous windows use. Also, blkid thought it was ntfs. This made me guess there was a stale superblock from the previous NTFS use that was confusing linux. So I took the swap partition off line, used dd to zero the beginning of it, and did mkswap again. All is now working. IMHO this is a bug in mkswap - it should make any arbitrary partition into a swap partition no matter what its previous content. --