[PATCH v2 repost 6/7] mm: add the related functions to get free page info

Liang Li
2016-07-27T01:23:35Z

Save the free page info into a page bitmap, will be used in virtio
balloon device driver.

Signed-off-by: Liang Li <liang.z.li@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Amit Shah <amit.shah@redhat.com>
---
mm/page_alloc.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7da61ad..3ad8b10 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4523,6 +4523,52 @@ unsigned long get_max_pfn(void)
}
EXPORT_SYMBOL(get_max_pfn);

+static void mark_free_pages_bitmap(struct zone *zone, unsigned long start_pfn,
+ unsigned long end_pfn, unsigned long *bitmap, unsigned long len)
+{
+ unsigned long pfn, flags, page_num;
+ unsigned int order, t;
+ struct list_head *curr;
+
+ if (zone_is_empty(zone))
+ return;
+ end_pfn = min(start_pfn + len, end_pfn);
+ spin_lock_irqsave(&zone->lock, flags);
+
+ for_each_migratetype_order(order, t) {
+ list_for_each(curr, &zone->free_area[order].free_list[t]) {
+ pfn = page_to_pfn(list_entry(curr, struct page, lru));
+ if (pfn >= start_pfn && pfn <= end_pfn) {
+ page_num = 1UL << order;
+ if (pfn + page_num > end_pfn)
+ page_num = end_pfn - pfn;
+ bitmap_set(bitmap, pfn - start_pfn, page_num);
+ }
+ }
+ }
+
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+int get_free_pages(unsigned long start_pfn, unsigned long end_pfn,
+ unsigned long *bitmap, unsigned long len)
+{
+ struct zone *zone;
+ int ret = 0;
+
+ if (bitmap == NULL || start_pfn > end_pfn || start_pfn >= max_pfn)
+ return 0;
+ if (end_pfn < max_pfn)
+ ret = 1;
+ if (end_pfn >= max_pfn)
+ ret = 0;
+
+ for_each_populated_zone(zone)
+ mark_free_pages_bitmap(zone, start_pfn, end_pfn, bitmap, len);
+ return ret;
+}
+EXPORT_SYMBOL(get_free_pages);
+
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
--
1.9.1