1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 2b17ad5b4b32..43f9f02c7db0 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -412,8 +412,16 @@ static int __init balloon_init(void)
 
         register_balloon(&balloon_sysdev);
 
-        /* Initialise the balloon with excess memory space. */
-        extra_pfn_end = min(e820_end_of_ram_pfn(),
+        /*
+         * Initialise the balloon with excess memory space.  We need
+         * to make sure we don't add memory which doesn't exist or
+         * logically exist.  The E820 map can be trimmed to be smaller
+         * than the amount of physical memory due to the mem= command
+         * line parameter.  And if this is a 32-bit non-HIGHMEM kernel
+         * on a system with memory which requires highmem to access,
+         * don't try to use it.
+         */
+        extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()),
                             (unsigned long)PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size));
         for (pfn = PFN_UP(xen_extra_mem_start);
              pfn < extra_pfn_end;