2 files changed, 12 insertions, 4 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ffee2f743418..2be8d9b5e46f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -145,6 +145,15 @@ extern pgprot_t protection_map[16];
 #define FAULT_FLAG_WRITE        0x01    /* Fault was a write access */
 #define FAULT_FLAG_NONLINEAR    0x02    /* Fault was via a nonlinear mapping */
 
+static inline int is_linear_pfn_mapping(struct vm_area_struct *vma)
+{
+        return ((vma->vm_flags & VM_PFNMAP) && vma->vm_pgoff);
+}
+
+static inline int is_pfn_mapping(struct vm_area_struct *vma)
+{
+        return (vma->vm_flags & VM_PFNMAP);
+}
 
 /*
  * vm_fault is filled by the the pagefault handler and passed to the vma's
diff --git a/mm/memory.c b/mm/memory.c
index 164951c47305..cef95c8c77fa 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1575,11 +1575,10 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
          * behaviour that some programs depend on. We mark the "original"
          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
          */
-        if (is_cow_mapping(vma->vm_flags)) {
-                if (addr != vma->vm_start || end != vma->vm_end)
-                        return -EINVAL;
+        if (addr == vma->vm_start && end == vma->vm_end)
                 vma->vm_pgoff = pfn;
-        }
+        else if (is_cow_mapping(vma->vm_flags))
+                return -EINVAL;
 
         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;