mm/memory_hotplug: VM_BUG if nid is too large.
mm/page_alloc: in page_outside_zone_boundaries(), avoid premature decisions.

With some code that expands the zone boundaries, VM_BUG_ON(bad_range()) was being triggered.

Previously, page_outside_zone_boundaries() decided that once it detected
a page outside the boundaries, it was certainly outside even if the
seqlock indicated the data was invalid & needed to be reread. This
methodology _almost_ works because zones are only ever grown. However,
becase the zone span is stored as a start and a length, some expantions
momentarily appear as shifts to the left (when the zone_start_pfn is
assigned prior to zone_spanned_pages).

If we want to remove the seqlock around zone_start_pfn & zone
spanned_pages, always writing the spanned_pages first, issuing a memory
barrier, and then writing the new zone_start_pfn _may_ work. The concern
there is that we could be seen as shrinking the span when zone_start_pfn
is written (the entire span would shift to the left). As there will be
no pages in the exsess span that actually belong to the zone being
manipulated, I don't expect there to be issues.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
mm/page_alloc: make pr_err() in page_outside_zone_boundaries() more useful
mm/page_alloc: use manage_pages instead of present pages when calculating default_zonelist_order()
mm: add a early_param "extra_nr_node_ids" to increase nr_node_ids above the minimum by a percentage.

For dynamic numa, sometimes the hypervisor we're running under will want
to split a single NUMA node into multiple NUMA nodes. If the number of
numa nodes is limited to the number avaliable when the system booted (as
it is on x86), we may not be able to fully adopt the new memory layout
provided by the hypervisor.

This option allows reserving some extra node ids as a percentage of the
boot time node ids. While not perfect (idealy nr_node_ids would be fully
dynamic), this allows decent functionality without invasive changes to
the SL{U,A}B allocators.