when md raid1 superblock is bad block, what happens

hi all, I have some questions about raid1 superblock and bad block.
when i create raid1 with two disks, the md will write superblock to the disk, if the location of superblock is bad , what will happens? report create error or add the block to bad-block-list and redirect superblock to another place? another question, how many bad blocks can be added to bad-block-list, when the bad-block-list is full, the raid will degrade?

Thank You
Wu Dong