[PATCH] mm: page_alloc: Make paranoid check in move_freepages a VM_BUG_ON

[Mel Gorman <mgorman@suse.de>]

Since 2.6.24 there has been a paranoid check in move_freepages that looks
up the zone of two pages. This is a very slow path and the only time I've
seen this bug trigger recently is when memory initialisation was broken
during patch development. Despite the fact it's a slow path, this patch
converts the check to a VM_BUG_ON anyway as it is served its purpose by now.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 mm/page_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0a7ed33..6fbd814 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1014,7 +1014,7 @@ int move_freepages(struct zone *zone,
 	 * Remove at a later date when no bug reports exist related to
 	 * grouping pages by mobility
 	 */
-	BUG_ON(page_zone(start_page) != page_zone(end_page));
+	VM_BUG_ON(page_zone(start_page) != page_zone(end_page));
 #endif
 
 	for (page = start_page; page <= end_page;) {

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