[PATCH 04/11] memory hotplug prep: fixup bad_range()

[Dave Hansen <haveblue@us.ibm.com>]

When doing memory hotplug operations, the size of existing zones can
obviously change.  This means that zone->zone_{start_pfn,spanned_pages}
can change.

There are currently no locks that protect these structure members.
However, they are rarely accessed at runtime.  Outside of swsusp, the
only place that I can find is bad_range().

So, split bad_range() up into two pieces: one that needs to be locked
and anther that doesn't.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

 memhotplug-dave/mm/page_alloc.c |   26 +++++++++++++++++++++-----
 1 files changed, 21 insertions(+), 5 deletions(-)

diff -puN mm/page_alloc.c~C5.1-bad_range-rework mm/page_alloc.c
--- memhotplug/mm/page_alloc.c~C5.1-bad_range-rework	2005-08-18 14:59:45.000000000 -0700
+++ memhotplug-dave/mm/page_alloc.c	2005-08-18 14:59:45.000000000 -0700
@@ -77,21 +77,37 @@ int min_free_kbytes = 1024;
 unsigned long __initdata nr_kernel_pages;
 unsigned long __initdata nr_all_pages;
 
-/*
- * Temporary debugging check for pages not lying within a given zone.
- */
-static int bad_range(struct zone *zone, struct page *page)
+static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
 {
 	if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages)
 		return 1;
 	if (page_to_pfn(page) < zone->zone_start_pfn)
 		return 1;
+
+	return 0;
+}
+
+static int page_is_consistent(struct zone *zone, struct page *page)
+{
 #ifdef CONFIG_HOLES_IN_ZONE
 	if (!pfn_valid(page_to_pfn(page)))
-		return 1;
+		return 0;
 #endif
 	if (zone != page_zone(page))
+		return 0;
+
+	return 1;
+}
+/*
+ * Temporary debugging check for pages not lying within a given zone.
+ */
+static int bad_range(struct zone *zone, struct page *page)
+{
+	if (page_outside_zone_boundaries(zone, page))
 		return 1;
+	if (!page_is_consistent(zone, page))
+		return 1;
+
 	return 0;
 }
 
_