From: Cody P Schafer <cody@linux.vnet.ibm.com>
Date: Thu, 7 Feb 2013 01:27:06 +0000 (+1100)
Subject: mm/page_alloc: add informative debugging message in page_outside_zone_boundaries()
X-Git-Tag: next-20130218~1^2~330
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=02129ddce60e851af19f88b273e1995b55c5c5d5;p=karo-tx-linux.git

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>
---

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;
 }