I found a bug in memory hot-add code for ia64.

IA64's code has copies of pgdat's array on each node to reduce memory
access over crossing node.  This array is used by NODE_DATA() macro.  When
new node is hot-added, this pgdat's array should be updated and copied on
new node too.

However, I used for_each_online_node() in scatter_node_data() to copy
it. This meant its array is not copied on new node.
Because initialization of structures for new node was halfway,
so online_node_map couldn't be set at this time.

To copy arrays on new node, I changed it to check value of pgdat_list[]
which is source array of copies.  I tested this patch with my Memory Hotadd
emulation on Tiger4.  This patch is for 2.6.17-git20.
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>