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Subject[RFC][PATCH 05/12] memory hotplug prep: fixup bad_range()
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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 2005-08-12 07:43:46.000000000 -0700
+++ memhotplug-dave/mm/page_alloc.c 2005-08-12 07:43:46.000000000 -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;
}

_
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