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-rw-r--r--drivers/xen/balloon.c12
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;