[PATCH] remove VM_DONTCOPY bogosities

Now that it's madvisable, remove two pieces of VM_DONTCOPY bogosity:

1. There was and is no logical reason why VM_DONTCOPY should be in the
   list of flags which forbid vma merging (and those drivers which set
   it are also setting VM_IO, which itself forbids the merge).

2. It's hard to understand the purpose of the VM_HUGETLB, VM_DONTCOPY
   block in vm_stat_account: but never mind, it's under CONFIG_HUGETLB,
   which (unlike CONFIG_HUGETLB_PAGE or CONFIG_HUGETLBFS) has never been
   defined.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index 47556d2b3e90ddbde4b0b8e69430ef5b3726e3af..0eb9894db6de6a0fa56caabbd1c002f0cea8e2c3 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -612,7 +612,7 @@ again:                      remove_next = 1 + (end > next->vm_end);
  * If the vma has a ->close operation then the driver probably needs to release
  * per-vma resources, so we don't attempt to merge those.
  */
-#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
+#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
 
 static inline int is_mergeable_vma(struct vm_area_struct *vma,
                        struct file *file, unsigned long vm_flags)
@@ -845,14 +845,6 @@ void vm_stat_account(struct mm_struct *mm, unsigned long flags,
        const unsigned long stack_flags
                = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
 
-#ifdef CONFIG_HUGETLB
-       if (flags & VM_HUGETLB) {
-               if (!(flags & VM_DONTCOPY))
-                       mm->shared_vm += pages;
-               return;
-       }
-#endif /* CONFIG_HUGETLB */
-
        if (file) {
                mm->shared_vm += pages;
                if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)