__rmqueue_fallback() will change the migratetype of pageblock, so it is possible that two continuous pageblocks have different migratetypes. When freeing all pages of the two blocks, they will be merged to 4M, and added to the buddy list which the migratetype is the first pageblock's. If later alloc some pages and split the 4M, the second pageblock will be added to the buddy list, and the migratetype is the first pageblock's, so it is different from the its pageblock's. That means the page in buddy list's migratetype is different from the page in pageblock's migratetype. This will make confusion. However,if we change the hotpath, it will be performance degradation, so any better ideas? Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx> --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 48aaf7b..5c91348 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -726,6 +726,9 @@ static inline void __free_one_page(struct page *page, list_add(&page->lru, &zone->free_area[order].free_list[migratetype]); out: zone->free_area[order].nr_free++; + /* If the range spans two pageblocks, reset the migratetype. */ + if (order > pageblock_order) + change_pageblock_range(page, order, migratetype); } static inline int free_pages_check(struct page *page) -- 2.0.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>