2 files changed, 12 insertions, 4 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;
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 2811bb988ea0..0009e489272c 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -423,7 +423,7 @@ static int find_unbound_irq(void)
         if (irq == start)
                 goto no_irqs;
 
-        res = irq_alloc_desc_at(irq, 0);
+        res = irq_alloc_desc_at(irq, -1);
 
         if (WARN_ON(res != irq))
                 return -1;
@@ -630,7 +630,7 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name)
         if (identity_mapped_irq(gsi) || (!xen_initial_domain() &&
                                 xen_pv_domain())) {
                 irq = gsi;
-                irq_alloc_desc_at(irq, 0);
+                irq_alloc_desc_at(irq, -1);
         } else
                 irq = find_unbound_irq();