get_total_pages_count() tries to get the page count of the system
RAM.
get_free_pages() is intend to construct a free pages bitmap by
traversing the free_list.
The free pages information will be sent to QEMU through virtio
and used for live migration optimization.
Signed-off-by: Liang Li <liang.z.li@xxxxxxxxx>
---
mm/page_alloc.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 838ca8bb..81922e6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3860,6 +3860,63 @@ void show_free_areas(unsigned int filter)
show_swap_cache_info();
}
+#define PFN_4G (0x100000000 >> PAGE_SHIFT)
+
+unsigned long get_total_pages_count(unsigned long low_mem)
+{
+ if (max_pfn >= PFN_4G) {
+ unsigned long pfn_gap = PFN_4G - (low_mem >> PAGE_SHIFT);
+
+ return max_pfn - pfn_gap;
+ } else
+ return max_pfn;
+}
+EXPORT_SYMBOL(get_total_pages_count);
+
+static void mark_free_pages_bitmap(struct zone *zone,
+ unsigned long *free_page_bitmap, unsigned long pfn_gap)
+{
+ unsigned long pfn, flags, i;
+ unsigned int order, t;
+ struct list_head *curr;
+
+ if (zone_is_empty(zone))
+ return;
+
+ 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));
+ for (i = 0; i < (1UL << order); i++) {
+ if ((pfn + i) >= PFN_4G)
+ set_bit_le(pfn + i - pfn_gap,
+ free_page_bitmap);
+ else
+ set_bit_le(pfn + i, free_page_bitmap);
+ }
+ }
+ }
+
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+void get_free_pages(unsigned long *free_page_bitmap,
+ unsigned long *free_pages_count,
+ unsigned long low_mem)
+{
+ struct zone *zone;
+ unsigned long pfn_gap;
+
+ pfn_gap = PFN_4G - (low_mem >> PAGE_SHIFT);
+ for_each_populated_zone(zone)
+ mark_free_pages_bitmap(zone, free_page_bitmap, pfn_gap);
+
+ *free_pages_count = global_page_state(NR_FREE_PAGES);
+}
+EXPORT_SYMBOL(get_free_pages);
+
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
--
1.8.3.1
--
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