unsigned long addr = vma->vm_start;
unsigned long end = vma->vm_end;
+ /*
+ * Don't copy ptes where a page fault will fill them correctly.
+ * Fork becomes much lighter when there are big shared or private
+ * readonly mappings. The tradeoff is that copy_page_range is more
+ * efficient than faulting.
+ */
+ if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_RESERVED))) {
+ if (!vma->anon_vma)
+ return 0;
+ }
+
if (is_vm_hugetlb_page(vma))
return copy_hugetlb_page_range(dst_mm, src_mm, vma);