From 235ae8a9f85092b967b70af731aa0494975de05d Mon Sep 17 00:00:00 2001
From: Nick Piggin <nickpiggin@yahoo.com.au>
Date: Sun, 28 Aug 2005 16:49:11 +1000
Subject: [PATCH] --- yaml --- r: 6222 b: refs/heads/master c:
 d992895ba2b27cf5adf1ba0ad6d27662adc54c5e h: refs/heads/master v: v3

---
 [refs]            |  2 +-
 trunk/mm/memory.c | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 540a73d390d0..1c4536c93f7f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 40193713df2cdb9c233b3fc2029ecdccb40cb1e4
+refs/heads/master: d992895ba2b27cf5adf1ba0ad6d27662adc54c5e
diff --git a/trunk/mm/memory.c b/trunk/mm/memory.c
index e046b7e4b530..a596c1172248 100644
--- a/trunk/mm/memory.c
+++ b/trunk/mm/memory.c
@@ -498,6 +498,17 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	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);