mm: remain migratetype in freed page

The page allocator caches the pageblock information in page->private while
it is in the PCP freelists but this is overwritten with the order of the
page when freed to the buddy allocator.  This patch stores the migratetype
of the page in the page->index field so that it is available at all times
when the page remain in free_list.

This patch adds a new call site in __free_pages_ok so it might be overhead
a bit but it's for high order allocation.  So I believe damage isn't hurt.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2ccd7824faf828151d22a63243da23106a595db9..3da1fa00776bfa626a972444247d34d4f7a213e3 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -254,13 +254,13 @@ struct inode;
 /* It's valid only if the page is free path or free_list */
 static inline void set_freepage_migratetype(struct page *page, int migratetype)
 {
-       set_page_private(page, migratetype);
+       page->index = migratetype;
 }
 
 /* It's valid only if the page is free path or free_list */
 static inline int get_freepage_migratetype(struct page *page)
 {
-       return page_private(page);
+       return page->index;
 }
 
 /*

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7717f93f51aedda485f56d9e4b23feb69e62e05d..0e94f6485fd53e50d5db344cc154c1fbd1d7b5c5 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -728,6 +728,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
 {
        unsigned long flags;
        int wasMlocked = __TestClearPageMlocked(page);
+       int migratetype;
 
        if (!free_pages_prepare(page, order))
                return;
@@ -736,8 +737,9 @@ static void __free_pages_ok(struct page *page, unsigned int order)
        if (unlikely(wasMlocked))
                free_page_mlock(page);
        __count_vm_events(PGFREE, 1 << order);
-       free_one_page(page_zone(page), page, order,
-                                       get_pageblock_migratetype(page));
+       migratetype = get_pageblock_migratetype(page);
+       set_freepage_migratetype(page, migratetype);
+       free_one_page(page_zone(page), page, order, migratetype);
        local_irq_restore(flags);
 }
 
@@ -958,6 +960,7 @@ static int move_freepages(struct zone *zone,
                order = page_order(page);
                list_move(&page->lru,
                          &zone->free_area[order].free_list[migratetype]);
+               set_freepage_migratetype(page, migratetype);
                page += 1 << order;
                pages_moved += 1 << order;
        }