Messages in this thread Patch in this message | | | From | Joonsoo Kim <> | Subject | [PATCH 7/7] mm/page_alloc: don't merge MIGRATE_(CMA|ISOLATE) pages on buddy | Date | Thu, 9 Jan 2014 16:04:47 +0900 |
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If (MAX_ORDER-1) is greater than pageblock order, there is a possibility to merge different migratetype pages and to be linked in unintended freelist.
While I test CMA, CMA pages are merged and linked into MOVABLE freelist by above issue and then, the pages change their migratetype to UNMOVABLE by try_to_steal_freepages(). After that, CMA to this region always fail.
To prevent this, we should not merge the page on MIGRATE_(CMA|ISOLATE) freelist.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2548b42..ea99cee 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -581,6 +581,15 @@ static inline void __free_one_page(struct page *page, __mod_zone_freepage_state(zone, 1 << order, migratetype); } else { + int buddy_mt = get_buddy_migratetype(buddy); + + /* We don't want to merge cma, isolate pages */ + if (unlikely(order >= pageblock_order) && + migratetype != buddy_mt && + (migratetype >= MIGRATE_PCPTYPES || + buddy_mt >= MIGRATE_PCPTYPES)) { + break; + } list_del(&buddy->lru); zone->free_area[order].nr_free--; rmv_page_order(buddy); -- 1.7.9.5
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