mm: make defensive checks around PFN values registered for memory usage

There are a number of different views to how much memory is currently active.
There is the arch-independent zone-sizing view, the bootmem allocator and
memory models view.

Architectures register this information at different times and is not
necessarily in sync particularly with respect to some SPARSEMEM limitations.

This patch introduces mminit_validate_memmodel_limits() which is able to
validate and correct PFN ranges with respect to the memory model.  It is only
SPARSEMEM that currently validates itself.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index acab6ad326df..0adb66e711e6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3536,6 +3536,8 @@ void __init add_active_range(unsigned int nid, unsigned long start_pfn,
                         nid, start_pfn, end_pfn,
                         nr_nodemap_entries, MAX_ACTIVE_REGIONS);
 
+        mminit_validate_memmodel_limits(&start_pfn, &end_pfn);
+
         /* Merge with existing active regions if possible */
         for (i = 0; i < nr_nodemap_entries; i++) {
                 if (early_node_map[i].nid != nid)