While merging buddy free pages of a given order to make a higher order page,
the buddy allocator might coalesce pages belonging to *two* *different*
migratetypes of that order!
So, don't assume that both the buddies come from the same freelist;
instead, explicitly find out the migratetype info of the buddy page and use
it while merging the buddies.
Also, set the freepage migratetype of the buddy to the new one.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e31daf4..c40715c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -685,10 +685,14 @@ static inline void __free_one_page(struct page *page,
__mod_zone_freepage_state(zone, 1 << order,
migratetype);
} else {
+ int mt;
+
area = &zone->free_area[order];
- del_from_freelist(buddy, &area->free_list[migratetype]);
+ mt = get_freepage_migratetype(buddy);
+ del_from_freelist(buddy, &area->free_list[mt]);
area->nr_free--;
rmv_page_order(buddy);
+ set_freepage_migratetype(buddy, migratetype);
}
combined_idx = buddy_idx & page_idx;
page = page + (combined_idx - page_idx);
--
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