Merge tag 'ext4_for_linus_urgent' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / mm / page_isolation.c

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index d1473b2..c8778f7 100644 (file)
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -60,6 +60,7 @@ out:
                int migratetype = get_pageblock_migratetype(page);
 
                set_pageblock_migratetype(page, MIGRATE_ISOLATE);
+               zone->nr_isolate_pageblock++;
                nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
 
                __mod_zone_freepage_state(zone, -nr_pages, migratetype);
@@ -75,16 +76,54 @@ void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 {
        struct zone *zone;
        unsigned long flags, nr_pages;
+       struct page *isolated_page = NULL;
+       unsigned int order;
+       unsigned long page_idx, buddy_idx;
+       struct page *buddy;
 
        zone = page_zone(page);
        spin_lock_irqsave(&zone->lock, flags);
        if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
                goto out;
-       nr_pages = move_freepages_block(zone, page, migratetype);
-       __mod_zone_freepage_state(zone, nr_pages, migratetype);
+
+       /*
+        * Because freepage with more than pageblock_order on isolated
+        * pageblock is restricted to merge due to freepage counting problem,
+        * it is possible that there is free buddy page.
+        * move_freepages_block() doesn't care of merge so we need other
+        * approach in order to merge them. Isolation and free will make
+        * these pages to be merged.
+        */
+       if (PageBuddy(page)) {
+               order = page_order(page);
+               if (order >= pageblock_order) {
+                       page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
+                       buddy_idx = __find_buddy_index(page_idx, order);
+                       buddy = page + (buddy_idx - page_idx);
+
+                       if (!is_migrate_isolate_page(buddy)) {
+                               __isolate_free_page(page, order);
+                               set_page_refcounted(page);
+                               isolated_page = page;
+                       }
+               }
+       }
+
+       /*
+        * If we isolate freepage with more than pageblock_order, there
+        * should be no freepage in the range, so we could avoid costly
+        * pageblock scanning for freepage moving.
+        */
+       if (!isolated_page) {
+               nr_pages = move_freepages_block(zone, page, migratetype);
+               __mod_zone_freepage_state(zone, nr_pages, migratetype);
+       }
        set_pageblock_migratetype(page, migratetype);
+       zone->nr_isolate_pageblock--;
 out:
        spin_unlock_irqrestore(&zone->lock, flags);
+       if (isolated_page)
+               __free_pages(isolated_page, order);
 }
 
 static inline struct page *