[PATCH] mm/memblock: WARN_ON when nid differs from overlap region

[Wei Yang <weiyang@linux.vnet.ibm.com>]

Each memblock_region has nid to indicates the Node ID of this range. For
the overlap case, memblock_add_range() inserts the lower part and leave the
upper part as indicated in the overlapped region.

If the nid of the new range differs from the overlapped region, the
information recorded is not correct.

This patch adds a WARN_ON when the nid of the new range differs from the
overlapped region.

---

I am not familiar with the lower level topology, maybe this case will not
happen. 

If current implementation is based on the assumption, that overlapped
ranges' nid and flags are the same, I would suggest to add a comment to
indicates this background.

If the assumption is not correct, I suggest to add a WARN_ON or BUG_ON to
indicates this case.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
---
 mm/memblock.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/memblock.c b/mm/memblock.c
index 9318b56..09efe70 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -540,6 +540,9 @@ repeat:
 		 * area, insert that portion.
 		 */
 		if (rbase > base) {
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+			WARN_ON(nid != memblock_get_region_node(rgn));
+#endif
 			nr_new++;
 			if (insert)
 				memblock_insert_region(type, i++, base,
-- 
1.7.9.5

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