[PATCH 3.11 114/137] lib/btree.c: fix leak of whole btree nodes

[Luis Henriques]

3.11.10.15 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Minfei Huang <huangminfei at ucloud.cn>

commit c75b53af2f0043aff500af0a6f878497bef41bca upstream.

I use btree from 3.14-rc2 in my own module.  When the btree module is
removed, a warning arises:

 kmem_cache_destroy btree_node: Slab cache still has objects
 CPU: 13 PID: 9150 Comm: rmmod Tainted: GF          O 3.14.0-rc2 #1
 Hardware name: Inspur NF5270M3/NF5270M3, BIOS CHEETAH_2.1.3 09/10/2013
 Call Trace:
   dump_stack+0x49/0x5d
   kmem_cache_destroy+0xcf/0xe0
   btree_module_exit+0x10/0x12 [btree]
   SyS_delete_module+0x198/0x1f0
   system_call_fastpath+0x16/0x1b

The cause is that it doesn't release the last btree node, when height = 1
and fill = 1.

[akpm at linux-foundation.org: remove unneeded test of NULL]
Signed-off-by: Minfei Huang <huangminfei at ucloud.cn>
Cc: Joern Engel <joern at logfs.org>
Cc: Johannes Berg <johannes at sipsolutions.net>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 lib/btree.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/btree.c b/lib/btree.c
index f9a484676cb6..4264871ea1a0 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -198,6 +198,7 @@ EXPORT_SYMBOL_GPL(btree_init);
 
 void btree_destroy(struct btree_head *head)
 {
+	mempool_free(head->node, head->mempool);
 	mempool_destroy(head->mempool);
 	head->mempool = NULL;
 }
-- 
1.9.1