diff -r 4ac8bc60c000 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c	Tue Feb 10 05:51:00 2009 +0000
+++ b/xen/common/page_alloc.c	Thu Feb 12 20:32:15 2009 -0700
@@ -931,6 +934,53 @@ void free_domheap_pages(struct page_info
         put_domain(d);
 }
 
+struct page_info *reassign_domheap_pages(struct domain *new,
+    struct page_info *pg, unsigned int order)
+{
+    struct domain *old = page_get_owner(pg);
+    struct domain *lock = (old != NULL) ? old : new;
+    int npages = 1 << order;
+    int i;
+
+    ASSERT(!in_irq());
+    ASSERT(!is_xen_heap_page(pg));
+    ASSERT((old != NULL) || (new != NULL));
+    if ( (new != NULL) && (new->tot_pages + npages > new->max_pages) )
+        return NULL;
+    spin_lock_recursive(&lock->page_alloc_lock);
+    if ( old != NULL )
+    {
+        ASSERT(old->tot_pages > npages);
+        old->tot_pages -= 1 << order;
+    }
+    if ( new != NULL )
+    {
+        ASSERT(new->tot_pages != 0);
+        new->tot_pages += npages;
+    }
+    for ( i = 0; i < (1 << order); i++ )
+    {
+        if ( old != NULL )
+        {
+            ASSERT(page_get_owner(&pg[i])==old);
+            ASSERT(pg[i].count_info & (PGC_allocated | 1));
+            pg[i].count_info &= ~(PGC_allocated | 1);
+            page_list_del(&pg[i], &old->page_list);
+        }
+        page_set_owner(&pg[i], new);
+        wmb(); /* Domain pointer must be visible before updating refcnt. */
+        if ( new != NULL )
+        {
+            ASSERT(page_get_owner(&pg[i])==NULL);
+            ASSERT((pg[i].count_info & ~(PGC_allocated | 1)) == 0);
+            pg[i].count_info = PGC_allocated | 1;
+            page_list_add_tail(&pg[i], &new->page_list);
+        }
+    }
+    spin_unlock_recursive(&lock->page_alloc_lock);
+    return pg;
+}
+
 unsigned long avail_domheap_pages_region(
     unsigned int node, unsigned int min_width, unsigned int max_width)
 {