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Subject[patch 6/12] mm: remove bad_range
Date
bad_range is supposed to be a temporary check. It would be a pity to throw
it out. Make it depend on CONFIG_DEBUG_VM instead.

CONFIG_HOLES_IN_ZONE systems were relying on this to check pfn_valid in
the page allocator. Add that to page_is_buddy instead.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c
+++ linux-2.6/mm/page_alloc.c
@@ -81,6 +81,7 @@ int min_free_kbytes = 1024;
unsigned long __initdata nr_kernel_pages;
unsigned long __initdata nr_all_pages;

+#ifdef CONFIG_DEBUG_VM
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
{
int ret = 0;
@@ -122,6 +123,13 @@ static int bad_range(struct zone *zone,
return 0;
}

+#else
+static inline int bad_range(struct zone *zone, struct page *page)
+{
+ return 0;
+}
+#endif
+
static void bad_page(const char *function, struct page *page)
{
printk(KERN_EMERG "Bad page state at %s (in process '%s', page %p)\n",
@@ -261,14 +269,20 @@ __find_combined_index(unsigned long page
/*
* This function checks whether a page is free && is the buddy
* we can do coalesce a page and its buddy if
- * (a) the buddy is free &&
- * (b) the buddy is on the buddy system &&
- * (c) a page and its buddy have the same order.
+ * (a) the buddy is not in a hole &&
+ * (b) the buddy is free &&
+ * (c) the buddy is on the buddy system &&
+ * (d) a page and its buddy have the same order.
* for recording page's order, we use page_private(page) and PG_private.
*
*/
static inline int page_is_buddy(struct page *page, int order)
{
+#ifdef CONFIG_HOLES_IN_ZONE
+ if (!pfn_valid(page_to_pfn(page)))
+ return 0;
+#endif
+
if (PagePrivate(page) &&
(page_order(page) == order) &&
page_count(page) == 0)
@@ -320,17 +334,15 @@ static inline void __free_pages_bulk (st
struct free_area *area;
struct page *buddy;

- combined_idx = __find_combined_index(page_idx, order);
buddy = __page_find_buddy(page, page_idx, order);
-
- if (bad_range(zone, buddy))
- break;
if (!page_is_buddy(buddy, order))
break; /* Move the buddy up one level. */
+
list_del(&buddy->lru);
area = zone->free_area + order;
area->nr_free--;
rmv_page_order(buddy);
+ combined_idx = __find_combined_index(page_idx, order);
page = page + (combined_idx - page_idx);
page_idx = combined_idx;
order++;
Index: linux-2.6/lib/Kconfig.debug
===================================================================
--- linux-2.6.orig/lib/Kconfig.debug
+++ linux-2.6/lib/Kconfig.debug
@@ -172,7 +172,8 @@ config DEBUG_VM
bool "Debug VM"
depends on DEBUG_KERNEL
help
- Enable this to debug the virtual-memory system.
+ Enable this to turn on extended checks in the virtual-memory system
+ that may impact performance.

If unsure, say N.

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