[PATCH] prio_tree: kill vma_prio_tree_init()

vma_prio_tree_insert() relies on the fact, that vma was
vma_prio_tree_init()'ed.

Content of vma->shared should be considered undefined, until this vma is
inserted into i_mmap/i_mmap_nonlinear.  It's better to do proper
initialization in vma_prio_tree_add/insert.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Rajesh Venkatasubramanian <vrajesh@umich.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/mm.h

@@ -598,14 +598,6 @@ extern void show_mem(void);
 extern void si_meminfo(struct sysinfo * val);
 extern void si_meminfo_node(struct sysinfo *val, int nid);
 
-static inline void vma_prio_tree_init(struct vm_area_struct *vma)
-{
-	vma->shared.vm_set.list.next = NULL;
-	vma->shared.vm_set.list.prev = NULL;
-	vma->shared.vm_set.parent = NULL;
-	vma->shared.vm_set.head = NULL;
-}
-
 /* prio_tree.c */
 void vma_prio_tree_add(struct vm_area_struct *, struct vm_area_struct *old);
 void vma_prio_tree_insert(struct vm_area_struct *, struct prio_tree_root *);
@@ -614,6 +606,13 @@ struct vm_area_struct *vma_prio_tree_next(
 	struct vm_area_struct *, struct prio_tree_root *,
 	struct prio_tree_iter *, pgoff_t begin, pgoff_t end);
 
+static inline void vma_nonlinear_insert(struct vm_area_struct *vma,
+					struct list_head *list)
+{
+	vma->shared.vm_set.parent = NULL;
+	list_add_tail(&vma->shared.vm_set.list, list);
+}
+
 /* mmap.c */
 extern void vma_adjust(struct vm_area_struct *vma, unsigned long start,
 	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert);

kernel/fork.c

@@ -324,7 +324,6 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 		tmp->vm_mm = mm;
 		tmp->vm_next = NULL;
 		anon_vma_link(tmp);
-		vma_prio_tree_init(tmp);
 		file = tmp->vm_file;
 		if (file) {
 			struct inode *inode = file->f_dentry->d_inode;

mm/fremap.c

@@ -220,9 +220,7 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
 			flush_dcache_mmap_lock(mapping);
 			vma->vm_flags |= VM_NONLINEAR;
 			vma_prio_tree_remove(vma, &mapping->i_mmap);
-			vma_prio_tree_init(vma);
-			list_add_tail(&vma->shared.vm_set.list,
-					&mapping->i_mmap_nonlinear);
+			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 			flush_dcache_mmap_unlock(mapping);
 			spin_unlock(&mapping->i_mmap_lock);
 		}

mm/mmap.c

@@ -279,8 +279,7 @@ static inline void __vma_link_file(struct vm_area_struct *vma)
 
 		flush_dcache_mmap_lock(mapping);
 		if (unlikely(vma->vm_flags & VM_NONLINEAR))
-			list_add_tail(&vma->shared.vm_set.list,
-					&mapping->i_mmap_nonlinear);
+			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 		else
 			vma_prio_tree_insert(vma, &mapping->i_mmap);
 		flush_dcache_mmap_unlock(mapping);
@@ -449,11 +448,8 @@ again:			remove_next = 1 + (end > next->vm_end);
 	}
 
 	if (root) {
-		if (adjust_next) {
-			vma_prio_tree_init(next);
+		if (adjust_next)
 			vma_prio_tree_insert(next, root);
-		}
-		vma_prio_tree_init(vma);
 		vma_prio_tree_insert(vma, root);
 		flush_dcache_mmap_unlock(mapping);
 	}
@@ -1489,7 +1485,6 @@ int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
 
 	/* most fields are the same, copy all, and then fixup */
 	*new = *vma;
-	vma_prio_tree_init(new);
 
 	if (new_below)
 		new->vm_end = addr;
@@ -1802,7 +1797,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 		new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 		if (new_vma) {
 			*new_vma = *vma;
-			vma_prio_tree_init(new_vma);
 			pol = mpol_copy(vma_policy(vma));
 			if (IS_ERR(pol)) {
 				kmem_cache_free(vm_area_cachep, new_vma);

mm/prio_tree.c

@@ -538,6 +538,9 @@ void vma_prio_tree_add(struct vm_area_struct *vma, struct vm_area_struct *old)
 	BUG_ON(RADIX_INDEX(vma) != RADIX_INDEX(old));
 	BUG_ON(HEAP_INDEX(vma) != HEAP_INDEX(old));
 
+	vma->shared.vm_set.head = NULL;
+	vma->shared.vm_set.parent = NULL;
+
 	if (!old->shared.vm_set.parent)
 		list_add(&vma->shared.vm_set.list,
 				&old->shared.vm_set.list);
@@ -557,6 +560,8 @@ void vma_prio_tree_insert(struct vm_area_struct *vma,
 	struct prio_tree_node *ptr;
 	struct vm_area_struct *old;
 
+	vma->shared.vm_set.head = NULL;
+
 	ptr = prio_tree_insert(root, &vma->shared.prio_tree_node);
 	if (ptr != &vma->shared.prio_tree_node) {
 		old = prio_tree_entry(ptr, struct vm_area_struct,