1 files changed, 18 insertions, 6 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 37d06ea624aa..61a6ac8fa8fc 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -399,11 +399,25 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
                         state = BP_EAGAIN;
                         break;
                 }
+                scrub_page(page);
 
-                pfn = page_to_pfn(page);
-                frame_list[i] = pfn_to_mfn(pfn);
+                frame_list[i] = page_to_pfn(page);
+        }
 
-                scrub_page(page);
+        /*
+         * Ensure that ballooned highmem pages don't have kmaps.
+         *
+         * Do this before changing the p2m as kmap_flush_unused()
+         * reads PTEs to obtain pages (and hence needs the original
+         * p2m entry).
+         */
+        kmap_flush_unused();
+
+        /* Update direct mapping, invalidate P2M, and add to balloon. */
+        for (i = 0; i < nr_pages; i++) {
+                pfn = frame_list[i];
+                frame_list[i] = pfn_to_mfn(pfn);
+                page = pfn_to_page(pfn);
 
 #ifdef CONFIG_XEN_HAVE_PVMMU
                 /*
@@ -429,11 +443,9 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
                 }
 #endif
 
-                balloon_append(pfn_to_page(pfn));
+                balloon_append(page);
         }
 
-        /* Ensure that ballooned highmem pages don't have kmaps. */
-        kmap_flush_unused();
         flush_tlb_all();
 
         set_xen_guest_handle(reservation.extent_start, frame_list);