[PATCH] fix uninitialised vma list_head

From Zach Brown.  Lots of places forget to initialise list_heads in
vm_area_structs, and other places then go and test the state of those
list_heads.

Plug the gaps for now, Zach is working on a broader cleanup.

fs/exec.c

@@ -400,6 +400,7 @@ int setup_arg_pages(struct linux_binprm *bprm)
 		mpnt->vm_ops = NULL;
 		mpnt->vm_pgoff = 0;
 		mpnt->vm_file = NULL;
+		INIT_LIST_HEAD(&mpnt->shared);
 		mpnt->vm_private_data = (void *) 0;
 		insert_vm_struct(mm, mpnt);
 		mm->total_vm = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;

kernel/fork.c

@@ -246,6 +246,7 @@ static inline int dup_mmap(struct mm_struct * mm)
 		tmp->vm_mm = mm;
 		tmp->vm_next = NULL;
 		file = tmp->vm_file;
+		INIT_LIST_HEAD(&tmp->shared);
 		if (file) {
 			struct inode *inode = file->f_dentry->d_inode;
 			get_file(file);

mm/mmap.c

@@ -553,6 +553,7 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 	vma->vm_file = NULL;
 	vma->vm_private_data = NULL;
 	vma->vm_raend = 0;
+	INIT_LIST_HEAD(&vma->shared);
 
 	if (file) {
 		error = -EINVAL;
@@ -1052,6 +1053,8 @@ int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
 	/* most fields are the same, copy all, and then fixup */
 	*new = *vma;
 
+	INIT_LIST_HEAD(&new->shared);
+
 	if (new_below) {
 		new->vm_end = addr;
 		vma->vm_start = addr;
@@ -1215,6 +1218,7 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
 	vma->vm_pgoff = 0;
 	vma->vm_file = NULL;
 	vma->vm_private_data = NULL;
+	INIT_LIST_HEAD(&vma->shared);
 
 	vma_link(mm, vma, prev, rb_link, rb_parent);
 

mm/mremap.c

@@ -227,6 +227,7 @@ static inline unsigned long move_vma(struct vm_area_struct * vma,
 	if (!move_page_tables(vma, new_addr, addr, old_len)) {
 		if (allocated_vma) {
 			*new_vma = *vma;
+			INIT_LIST_HEAD(&new_vma->shared);
 			new_vma->vm_start = new_addr;
 			new_vma->vm_end = new_addr+new_len;
 			new_vma->vm_pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;