[PATCH v3 4/4] mm/vmap: move BUG_ON() check to the unlink_va()

Uladzislau Rezki (Sony)
2019-05-27T09:39:08Z

Move the BUG_ON()/RB_EMPTY_NODE() check under unlink_va()
function, it means if an empty node gets freed it is a BUG
thus is considered as faulty behaviour.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
mm/vmalloc.c | 24 +++++++++---------------
1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 371aba9a4bf1..340959b81228 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -533,20 +533,16 @@ link_va(struct vmap_area *va, struct rb_root *root,
static __always_inline void
unlink_va(struct vmap_area *va, struct rb_root *root)
{
- /*
- * During merging a VA node can be empty, therefore
- * not linked with the tree nor list. Just check it.
- */
- if (!RB_EMPTY_NODE(&va->rb_node)) {
- if (root == &free_vmap_area_root)
- rb_erase_augmented(&va->rb_node,
- root, &free_vmap_area_rb_augment_cb);
- else
- rb_erase(&va->rb_node, root);
+ BUG_ON(RB_EMPTY_NODE(&va->rb_node));

- list_del(&va->list);
- RB_CLEAR_NODE(&va->rb_node);
- }
+ if (root == &free_vmap_area_root)
+ rb_erase_augmented(&va->rb_node,
+ root, &free_vmap_area_rb_augment_cb);
+ else
+ rb_erase(&va->rb_node, root);
+
+ list_del(&va->list);
+ RB_CLEAR_NODE(&va->rb_node);
}

#if DEBUG_AUGMENT_PROPAGATE_CHECK
@@ -1187,8 +1183,6 @@ EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);

static void __free_vmap_area(struct vmap_area *va)
{
- BUG_ON(RB_EMPTY_NODE(&va->rb_node));
-
/*
* Remove from the busy tree/list.
*/
--
2.11.0