1 files changed, 16 insertions, 4 deletions

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index baff1da354e0..af78e50ca6ce 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -86,6 +86,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
         pgprot_t prot;
         int retval;
         void __iomem *ret_addr;
+        int ram_region;
 
         /* Don't allow wraparound or zero size */
         last_addr = phys_addr + size - 1;
@@ -108,12 +109,23 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
         /*
          * Don't allow anybody to remap normal RAM that we're using..
          */
-        pfn      = phys_addr >> PAGE_SHIFT;
-        last_pfn = last_addr >> PAGE_SHIFT;
-        if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
-                                  __ioremap_check_ram) == 1)
+        /* First check if whole region can be identified as RAM or not */
+        ram_region = region_is_ram(phys_addr, size);
+        if (ram_region > 0) {
+                WARN_ONCE(1, "ioremap on RAM at 0x%lx - 0x%lx\n",
+                                (unsigned long int)phys_addr,
+                                (unsigned long int)last_addr);
                 return NULL;
+        }
 
+        /* If could not be identified(-1), check page by page */
+        if (ram_region < 0) {
+                pfn      = phys_addr >> PAGE_SHIFT;
+                last_pfn = last_addr >> PAGE_SHIFT;
+                if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
+                                          __ioremap_check_ram) == 1)
+                        return NULL;
+        }
         /*
          * Mappings have to be page-aligned
          */