[PATCH 1/3] zone init check and report unaligned zone boundries

[Andy Whitcroft <apw@shadowen.org>]

zone init check and report unaligned zone boundries

We have a number of strict constraints on the layout of struct
page's for use with the buddy allocator.  One of which is that zone
boundries must occur at MAX_ORDER page boundries.  Add a check for
this during init.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
---
 include/linux/mmzone.h |    5 +++++
 mm/page_alloc.c        |    4 ++++
 2 files changed, 9 insertions(+)
diff -upN reference/include/linux/mmzone.h current/include/linux/mmzone.h
--- reference/include/linux/mmzone.h
+++ current/include/linux/mmzone.h
@@ -388,6 +388,11 @@ static inline int is_dma(struct zone *zo
 	return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
 }
 
+static inline unsigned long zone_boundry_align_pfn(unsigned long pfn)
+{
+	return pfn & ~((1 << MAX_ORDER) - 1);
+}
+
 /* These two functions are used to setup the per zone pages min values */
 struct ctl_table;
 struct file;
diff -upN reference/mm/page_alloc.c current/mm/page_alloc.c
--- reference/mm/page_alloc.c
+++ current/mm/page_alloc.c
@@ -2078,6 +2078,10 @@ static void __init free_area_init_core(s
 		struct zone *zone = pgdat->node_zones + j;
 		unsigned long size, realsize;
 
+		if (zone_boundry_align_pfn(zone_start_pfn) != zone_start_pfn)
+			printk(KERN_CRIT "node %d zone %s missaligned "
+					"start pfn\n", nid, zone_names[j]);
+
 		realsize = size = zones_size[j];
 		if (zholes_size)
 			realsize -= zholes_size[j];