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Subject[PATCH v5 4/4] mm/vmalloc.c: switch to WARN_ON() and move it under unlink_va()
Date
Trigger a warning if an object that is about to be freed is detached.
We used to have a BUG_ON(), but even though it is considered as faulty
behaviour that is not a good reason to break a system.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
mm/vmalloc.c | 25 ++++++++++---------------
1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a4bdf5fc3512..899a250e4eb6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -534,20 +534,17 @@ 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);
+ if (WARN_ON(RB_EMPTY_NODE(&va->rb_node)))
+ return;

- 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
@@ -1162,8 +1159,6 @@ 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
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