[RFC PATCH v3 31/35] mm: Add a way to request pages of a particular region from the region allocator

[Srivatsa S. Bhat]

When moving freepages from one migratetype to another (using move_freepages()
or equivalent), we might encounter situations in which we would like to move
pages that are in the region allocator. In such cases, we need a way to
request pages of a particular region from the region allocator.

We already have the code to perform the heavy-lifting of actually moving the
pages of a region from the region allocator to a requested freelist or
migratetype. So just reorganize that code in such a way that we can also
pin-point a region and specify that we want the region allocator to allocate
pages from that particular region.

Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com>
---

 mm/page_alloc.c |   40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3f49ca8..fc530ff 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1002,24 +1002,18 @@ static void add_to_region_allocator(struct zone *z, 
struct free_list *free_list,
                *next_region = region_id;
 }
 
-/* Delete freepages from the region allocator and add them to buddy freelists 
*/
-static int del_from_region_allocator(struct zone *zone, unsigned int order,
-                                    int migratetype)
+static void __del_from_region_allocator(struct zone *zone, unsigned int order,
+                                       int migratetype, int region_id)
 {
        struct region_allocator *reg_alloc;
        struct free_area_region *reg_area;
        struct list_head *ralloc_list;
        struct free_list *free_list;
        unsigned long nr_pages;
-       int next_region;
+       struct page *page;
 
        reg_alloc = &zone->region_allocator;
-
-       next_region = reg_alloc->next_region;
-       if (next_region < 0)
-               return -ENOMEM;
-
-       reg_area = &reg_alloc->region[next_region].region_area[order];
+       reg_area = &reg_alloc->region[region_id].region_area[order];
        ralloc_list = &reg_area->list;
 
        list_for_each_entry(page, ralloc_list, lru)
@@ -1028,20 +1022,34 @@ static int del_from_region_allocator(struct zone *zone, 
unsigned int order,
        free_list = &zone->free_area[order].free_list[migratetype];
 
        nr_pages = add_to_freelist_bulk(ralloc_list, free_list, order,
-                                       next_region);
+                                       region_id);
 
        reg_area->nr_free -= nr_pages;
        WARN_ON(reg_area->nr_free != 0);
 
        /* Pick a new next_region */
-       clear_bit(next_region, reg_alloc->ralloc_mask);
-       next_region = find_first_bit(reg_alloc->ralloc_mask,
+       clear_bit(region_id, reg_alloc->ralloc_mask);
+       region_id = find_first_bit(reg_alloc->ralloc_mask,
                                     MAX_NR_ZONE_REGIONS);
 
-       if (next_region >= MAX_NR_ZONE_REGIONS)
-               next_region = -1; /* No free regions available */
+       if (region_id >= MAX_NR_ZONE_REGIONS)
+               region_id = -1; /* No free regions available */
+
+       reg_alloc->next_region = region_id;
+}
+
+/* Delete freepages from the region allocator and add them to buddy freelists 
*/
+static int del_from_region_allocator(struct zone *zone, unsigned int order,
+                                    int migratetype)
+{
+       int next_region;
+
+       next_region = zone->region_allocator.next_region;
+
+       if (next_region < 0)
+               return -ENOMEM;
 
-       reg_alloc->next_region = next_region;
+       __del_from_region_allocator(zone, order, migratetype, next_region);
 
        return 0;
 }

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/