On Thu, 8 May 2014 12:21:12 +0800 Minfei Huang <huangmin...@ucloud.cn> wrote:
> 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.
Thanks.
> --- a/lib/btree.c
> +++ b/lib/btree.c
> @@ -198,6 +198,8 @@ EXPORT_SYMBOL_GPL(btree_init);
>
> void btree_destroy(struct btree_head *head)
> {
> + if (head->node)
> + mempool_free(head->node, head->mempool);
> mempool_destroy(head->mempool);
> head->mempool = NULL;
We don't really need the test - mempool_free(NULL, ...) is an OK thing
to do. We conventionally will rely upon this for optimisation reasons,
although not having the test can sometimes make the code less clear.
--- a/lib/btree.c~lib-btreec-fix-leak-of-whole-btree-nodes-fix
+++ a/lib/btree.c
@@ -198,8 +198,7 @@ EXPORT_SYMBOL_GPL(btree_init);
void btree_destroy(struct btree_head *head)
{
- if (head->node)
- mempool_free(head->node, head->mempool);
+ mempool_free(head->node, head->mempool);
mempool_destroy(head->mempool);
head->mempool = NULL;
}
_
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
