4 files changed, 28 insertions, 9 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. */
diff --git a/kernel/fork.c b/kernel/fork.c
index 856eac3ec52e..b7e9d60a675d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -300,7 +300,7 @@ out:
 #ifdef CONFIG_MMU
 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 {
-        struct vm_area_struct *mpnt, *tmp, **pprev;
+        struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
         struct rb_node **rb_link, *rb_parent;
         int retval;
         unsigned long charge;
@@ -328,6 +328,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
         if (retval)
                 goto out;
 
+        prev = NULL;
         for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
                 struct file *file;
 
@@ -359,7 +360,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                         goto fail_nomem_anon_vma_fork;
                 tmp->vm_flags &= ~VM_LOCKED;
                 tmp->vm_mm = mm;
-                tmp->vm_next = NULL;
+                tmp->vm_next = tmp->vm_prev = NULL;
                 file = tmp->vm_file;
                 if (file) {
                         struct inode *inode = file->f_path.dentry->d_inode;
@@ -392,6 +393,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                  */
                 *pprev = tmp;
                 pprev = &tmp->vm_next;
+                tmp->vm_prev = prev;
+                prev = tmp;
 
                 __vma_link_rb(mm, tmp, rb_link, rb_parent);
                 rb_link = &tmp->vm_rb.rb_right;
diff --git a/mm/mmap.c b/mm/mmap.c
index 31003338b978..331e51af38c9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -388,17 +388,23 @@ static inline void
 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
                 struct vm_area_struct *prev, struct rb_node *rb_parent)
 {
+        struct vm_area_struct *next;
+
+        vma->vm_prev = prev;
         if (prev) {
-                vma->vm_next = prev->vm_next;
+                next = prev->vm_next;
                 prev->vm_next = vma;
         } else {
                 mm->mmap = vma;
                 if (rb_parent)
-                        vma->vm_next = rb_entry(rb_parent,
+                        next = rb_entry(rb_parent,
                                         struct vm_area_struct, vm_rb);
                 else
-                        vma->vm_next = NULL;
+                        next = NULL;
         }
+        vma->vm_next = next;
+        if (next)
+                next->vm_prev = vma;
 }
 
 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
@@ -483,7 +489,11 @@ static inline void
 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
                 struct vm_area_struct *prev)
 {
-        prev->vm_next = vma->vm_next;
+        struct vm_area_struct *next = vma->vm_next;
+
+        prev->vm_next = next;
+        if (next)
+                next->vm_prev = prev;
         rb_erase(&vma->vm_rb, &mm->mm_rb);
         if (mm->mmap_cache == vma)
                 mm->mmap_cache = prev;
@@ -1915,6 +1925,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
         unsigned long addr;
 
         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
+        vma->vm_prev = NULL;
         do {
                 rb_erase(&vma->vm_rb, &mm->mm_rb);
                 mm->map_count--;
@@ -1922,6 +1933,8 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
                 vma = vma->vm_next;
         } while (vma && vma->vm_start < end);
         *insertion_point = vma;
+        if (vma)
+                vma->vm_prev = prev;
         tail_vma->vm_next = NULL;
         if (mm->unmap_area == arch_unmap_area)
                 addr = prev ? prev->vm_end : mm->mmap_base;
diff --git a/mm/nommu.c b/mm/nommu.c
index efa9a380335e..88ff091eb07a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -604,7 +604,7 @@ static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
  */
 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 {
-        struct vm_area_struct *pvma, **pp;
+        struct vm_area_struct *pvma, **pp, *next;
         struct address_space *mapping;
         struct rb_node **p, *parent;
 
@@ -664,8 +664,11 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
                         break;
         }
 
-        vma->vm_next = *pp;
+        next = *pp;
         *pp = vma;
+        vma->vm_next = next;
+        if (next)
+                next->vm_prev = vma;
 }
 
 /*