Re: [PATCH for-next 2/3] RDMA/rtrs: Fix rxe_dealloc_pd warning
From: Zhu Yanjun
Date: Fri Apr 14 2023 - 12:06:17 EST
在 2023/4/13 21:24, Leon Romanovsky 写道:
On Thu, Apr 13, 2023 at 08:12:15AM +0000, Zhijian Li (Fujitsu) wrote:
On 13/04/2023 15:35, Guoqing Jiang wrote:
Hi,
I take a closer look today.
On 4/12/23 09:15, Zhijian Li (Fujitsu) wrote:
On 11/04/2023 20:26, Leon Romanovsky wrote:
On Tue, Apr 11, 2023 at 02:43:46AM +0000, Zhijian Li (Fujitsu) wrote:
On 10/04/2023 21:10, Guoqing Jiang wrote:
On 4/10/23 20:08, Leon Romanovsky wrote:
On Mon, Apr 10, 2023 at 06:43:03AM +0000, Li Zhijian wrote:
The warning occurs when destroying PD whose reference count is not zero.
Precodition: clt_path->s.con_num is 2.
So 2 cm connection will be created as below:
CPU0 CPU1
init_conns { |
create_cm() // a. con[0] created |
| a'. rtrs_clt_rdma_cm_handler() {
| rtrs_rdma_addr_resolved()
| create_con_cq_qp(con); << con[0]
| }
| in this moment, refcnt of PD was increased to 2+
What do you mean "refcnt of PD"? usecnt in struct ib_pd or dev_ref.
I mean usecnt in struct ib_pd
|
create_cm() // b. cid = 1, failed |
destroy_con_cq_qp() |
rtrs_ib_dev_put() |
dev_free() |
ib_dealloc_pd(dev->ib_pd) << PD |
is destroyed, but refcnt is |
still greater than 0 |
Assuming you mean "pd->usecnt". We only allocate pd in con[0] by rtrs_ib_dev_find_or_add,
if con[1] failed to create cm, then alloc_path_reqs -> ib_alloc_mr -> atomic_inc(&pd->usecnt)
can't be triggered. Is there other places could increase the refcnt?
Yes, when create a qp, it will also associate to this PD, that also mean refcnt of PD will be increased.
When con[0](create_con_cq_qp) succeeded, refcnt of PD will be 2. and then when con[1] failed, since
QP didn't create, refcnt of PD is still 2. con[1]'s cleanup will destroy the PD(ib_dealloc_pd) since dev_ref = 1, after that its
refcnt is still 1.
Why is refcnt 1 in con[1] destruction phase? It seems to me like a bug.
Agree. We should find out why refcnt 1 and fix this problem.
Zhu Yanjun
Thanks