diff options
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index cefe6fe8d99..c54376a09f3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1208,6 +1208,51 @@ void split_page(struct page *page, unsigned int order) } /* + * Similar to split_page except the page is already free. As this is only + * being used for migration, the migratetype of the block also changes. + * As this is called with interrupts disabled, the caller is responsible + * for calling arch_alloc_page() and kernel_map_page() after interrupts + * are enabled. + * + * Note: this is probably too low level an operation for use in drivers. + * Please consult with lkml before using this in your driver. + */ +int split_free_page(struct page *page) +{ + unsigned int order; + unsigned long watermark; + struct zone *zone; + + BUG_ON(!PageBuddy(page)); + + zone = page_zone(page); + order = page_order(page); + + /* Obey watermarks as if the page was being allocated */ + watermark = low_wmark_pages(zone) + (1 << order); + if (!zone_watermark_ok(zone, 0, watermark, 0, 0)) + return 0; + + /* Remove page from free list */ + list_del(&page->lru); + zone->free_area[order].nr_free--; + rmv_page_order(page); + __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order)); + + /* Split into individual pages */ + set_page_refcounted(page); + split_page(page, order); + + if (order >= pageblock_order - 1) { + struct page *endpage = page + (1 << order) - 1; + for (; page < endpage; page += pageblock_nr_pages) + set_pageblock_migratetype(page, MIGRATE_MOVABLE); + } + + return 1 << order; +} + +/* * Really, prep_compound_page() should be called from __rmqueue_bulk(). But * we cheat by calling it from here, in the order > 0 path. Saves a branch * or two. |