1 files changed, 17 insertions, 4 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 3100333..331e51a 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;