I use the btree which pickes up the latest version of kernel source
3.14-rc2 in my own module. When the btree module is removed, a warning arised:
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
ffff881ff8643b18 ffff881ffdc23ea8 ffffffff815a4ecc 0000000000000000
ffff881ff8643ac0 ffff881ffdc23ec8 ffffffff811610df 0000000000000880
ffffffffa057da60 ffff881ffdc23ed8 ffffffffa057d57c ffff881ffdc23f78
Call Trace:
[<ffffffff815a4ecc>] dump_stack+0x49/0x5d
[<ffffffff811610df>] kmem_cache_destroy+0xcf/0xe0
[<ffffffffa057d57c>] btree_module_exit+0x10/0x12 [btree]
[<ffffffff810d7948>] SyS_delete_module+0x198/0x1f0
[<ffffffff815aac89>] ? retint_swapgs+0xe/0x13
[<ffffffff810a561d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
[<ffffffff812addde>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff815b3652>] system_call_fastpath+0x16/0x1b
The cause is that it doesn't release the last btree node,
when height = 1 and fill = 1.
Signed-off-by: Minfei Huang <[email protected]>
CC: Joern Engel <[email protected]>
CC: Johannes Berg <[email protected]>
---
lib/btree.c | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/lib/btree.c b/lib/btree.c
index f9a4846..fd17d26 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -444,6 +444,16 @@ static void btree_shrink(struct btree_head *head, struct btree_geo *geo)
mempool_free(node, head->mempool);
}
+static void btree_shrink_head(struct btree_head *head)
+{
+ if (head->height != 1)
+ return;
+
+ mempool_free(head->node, head->mempool);
+ head->node = NULL;
+ head->height--;
+}
+
static int btree_insert_level(struct btree_head *head, struct btree_geo *geo,
unsigned long *key, void *val, int level,
gfp_t gfp)
@@ -620,6 +630,8 @@ static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo,
rebalance(head, geo, key, level, node, fill - 1);
else if (fill - 1 == 1)
btree_shrink(head, geo);
+ else if (fill - 1 == 0)
+ btree_shrink_head(head);
}
return ret;
--
1.7.1