From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx> Subject: mm/vmalloc.c: switch to WARN_ON() and move it under unlink_va() 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. Link: http://lkml.kernel.org/r/20190606120411.8298-5-urezki@xxxxxxxxx Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Hillf Danton <hdanton@xxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Oleksiy Avramchenko <oleksiy.avramchenko@xxxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) --- a/mm/vmalloc.c~mm-vmallocc-switch-to-warn_on-and-move-it-under-unlink_va +++ a/mm/vmalloc.c @@ -534,20 +534,17 @@ link_va(struct vmap_area *va, struct rb_ 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_ static void __free_vmap_area(struct vmap_area *va) { - BUG_ON(RB_EMPTY_NODE(&va->rb_node)); - /* * Remove from the busy tree/list. */ _
