memory hotplug: alloc page from other node in memory online

memory hotplug: alloc page from other node in memory online

To initialize hotadded node, some pages are allocated.  At that time, the
node hasn't memory, this makes the allocation always fail.  In such case,
let's allocate pages from other nodes.

Signed-off-by: Shaohua Li <[email protected]>
Signed-off-by: Yakui Zhao <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>