From 02129ddce60e851af19f88b273e1995b55c5c5d5 Mon Sep 17 00:00:00 2001
From: Cody P Schafer <cody@linux.vnet.ibm.com>
Date: Thu, 7 Feb 2013 12:27:06 +1100
Subject: [PATCH] mm/page_alloc: add informative debugging message in
 page_outside_zone_boundaries()

Add a debug message which prints when a page is found outside of the
boundaries of the zone it should belong to. Format is:
	"page $pfn outside zone [ $start_pfn - $end_pfn ]"

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/page_alloc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cde32d2ffb9c..216bb912611d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -247,13 +247,20 @@ static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
 	int ret = 0;
 	unsigned seq;
 	unsigned long pfn = page_to_pfn(page);
+	unsigned long sp, start_pfn;
 
 	do {
 		seq = zone_span_seqbegin(zone);
+		start_pfn = zone->zone_start_pfn;
+		sp = zone->spanned_pages;
 		if (!zone_spans_pfn(zone, pfn))
 			ret = 1;
 	} while (zone_span_seqretry(zone, seq));
 
+	if (ret)
+		pr_debug("page %lu outside zone [ %lu - %lu ]\n",
+			pfn, start_pfn, start_pfn + sp);
+
 	return ret;
 }
 
-- 
2.39.5