2 files changed, 9 insertions, 3 deletions

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 4903a03ae876..59b7fc453277 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -410,9 +410,8 @@ void __init init_mem_mapping(void)
         /* the ISA range is always mapped regardless of memory holes */
         init_memory_mapping(0, ISA_END_ADDRESS);
 
-        /* xen has big range in reserved near end of ram, skip it at first */
-        addr = memblock_find_in_range(ISA_END_ADDRESS, end, PMD_SIZE,
-                         PAGE_SIZE);
+        /* xen has big range in reserved near end of ram, skip it at first.*/
+        addr = memblock_find_in_range(ISA_END_ADDRESS, end, PMD_SIZE, PMD_SIZE);
         real_end = addr + PMD_SIZE;
 
         /* step_size need to be small so pgt_buf from BRK could cover it */
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 2610bd93c896..657438858e83 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -563,6 +563,13 @@ int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
         if (base > __pa(high_memory-1))
                 return 0;
 
+        /*
+         * some areas in the middle of the kernel identity range
+         * are not mapped, like the PCI space.
+         */
+        if (!page_is_ram(base >> PAGE_SHIFT))
+                return 0;
+
         id_sz = (__pa(high_memory-1) <= base + size) ?
                                 __pa(high_memory) - base :
                                 size;