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-rw-r--r--mm/page_alloc.c30
1 files changed, 25 insertions, 5 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a6326c71b663..596180fedd3a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -475,6 +475,8 @@ static inline void __free_one_page(struct page *page,
int migratetype)
{
unsigned long page_idx;
+ unsigned long combined_idx;
+ struct page *buddy;
if (unlikely(PageCompound(page)))
if (unlikely(destroy_compound_page(page, order)))
@@ -488,9 +490,6 @@ static inline void __free_one_page(struct page *page,
VM_BUG_ON(bad_range(zone, page));
while (order < MAX_ORDER-1) {
- unsigned long combined_idx;
- struct page *buddy;
-
buddy = __page_find_buddy(page, page_idx, order);
if (!page_is_buddy(page, buddy, order))
break;
@@ -505,8 +504,29 @@ static inline void __free_one_page(struct page *page,
order++;
}
set_page_order(page, order);
- list_add(&page->lru,
- &zone->free_area[order].free_list[migratetype]);
+
+ /*
+ * If this is not the largest possible page, check if the buddy
+ * of the next-highest order is free. If it is, it's possible
+ * that pages are being freed that will coalesce soon. In case,
+ * that is happening, add the free page to the tail of the list
+ * so it's less likely to be used soon and more likely to be merged
+ * as a higher order page
+ */
+ if ((order < MAX_ORDER-1) && pfn_valid_within(page_to_pfn(buddy))) {
+ struct page *higher_page, *higher_buddy;
+ combined_idx = __find_combined_index(page_idx, order);
+ higher_page = page + combined_idx - page_idx;
+ higher_buddy = __page_find_buddy(higher_page, combined_idx, order + 1);
+ if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
+ list_add_tail(&page->lru,
+ &zone->free_area[order].free_list[migratetype]);
+ goto out;
+ }
+ }
+
+ list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
+out:
zone->free_area[order].nr_free++;
}