mm: make the vma list be doubly linked

It's a really simple list, and several of the users want to go backwards
in it to find the previous vma.  So rather than have to look up the
previous entry with 'find_vma_prev()' or something similar, just make it
doubly linked instead.

Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b8bb9a6a1f37..ee7e258627f9 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -134,7 +134,7 @@ struct vm_area_struct {
                                            within vm_mm. */
 
         /* linked list of VM areas per task, sorted by address */
-        struct vm_area_struct *vm_next;
+        struct vm_area_struct *vm_next, *vm_prev;
 
         pgprot_t vm_page_prot;          /* Access permissions of this VMA. */
         unsigned long vm_flags;         /* Flags, see mm.h. */