With the introduction of the region allocator, a freepage can be either
in one of the buddy freelists or in the region allocator. In cases where we
want to move freepages to a given migratetype's freelists, we will need to
know where they were originally located. So provide a helper to distinguish
whether the freepage resides in the region allocator or the buddy freelists.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ca7b959..ac04b45 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1048,6 +1048,37 @@ static int del_from_region_allocator(struct zone *zone, unsigned int order,
}
/*
+ * Return 1 if the page is in the region allocator, else return 0
+ * (which usually means that the page is in the buddy freelists).
+ */
+static int page_in_region_allocator(struct page *page)
+{
+ struct region_allocator *reg_alloc;
+ struct free_area_region *reg_area;
+ int order, region_id;
+
+ /* We keep only MAX_ORDER-1 pages in the region allocator */
+ order = page_order(page);
+ if (order != MAX_ORDER-1)
+ return 0;
+
+ /*
+ * It is sufficient to check if (any of) the pages belonging to
+ * that region are in the region allocator, because a page resides
+ * in the region allocator if and only if all the pages of that
+ * region are also in the region allocator.
+ */
+ region_id = page_zone_region_id(page);
+ reg_alloc = &page_zone(page)->region_allocator;
+ reg_area = ®_alloc->region[region_id].region_area[order];
+
+ if (reg_area->nr_free)
+ return 1;
+
+ return 0;
+}
+
+/*
* Freeing function for a buddy system allocator.
*
* The concept of a buddy system is to maintain direct-mapped table
--
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