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Message-ID: <8fe62e38-e43d-3d6c-624f-1c8ce5859788@linux.dev>
Date: Thu, 13 Apr 2023 15:35:44 +0800
From: Guoqing Jiang <guoqing.jiang@...ux.dev>
To: "Zhijian Li (Fujitsu)" <lizhijian@...itsu.com>,
Leon Romanovsky <leon@...nel.org>
Cc: "haris.iqbal@...os.com" <haris.iqbal@...os.com>,
"jinpu.wang@...os.com" <jinpu.wang@...os.com>,
"jgg@...pe.ca" <jgg@...pe.ca>,
"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH for-next 2/3] RDMA/rtrs: Fix rxe_dealloc_pd warning
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.
>>>>>> |
>>>>>> 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?
>>>>>> }
>>>>>>
>>>>>> Simply, Here we can avoid this warning by introducing conn own flag to
>>>>>> track if its cleanup should drop the PD.
>>>>>>
>>>>>> -----------------------------------------------
>>>>>> rnbd_client L597: Mapping device /dev/nvme0n1 on session client, (access_mode: rw, nr_poll_queues: 0)
>>>>>> ------------[ cut here ]------------
>>>>>> WARNING: CPU: 0 PID: 26407 at drivers/infiniband/sw/rxe/rxe_pool.c:256 __rxe_cleanup+0x13a/0x170 [rdma_rxe]
>>>>>> Modules linked in: rpcrdma rdma_ucm ib_iser rnbd_client libiscsi rtrs_client scsi_transport_iscsi rtrs_core rdma_cm iw_cm ib_cm crc32_generic rdma_rxe udp_tunnel ib_uverbs ib_core kmem device_dax nd_pmem dax_pmem nd_
>>>>>> vme crc32c_intel fuse nvme_core nfit libnvdimm dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua dm_mirror dm_region_hash dm_log dm_mod
>>>>>> CPU: 0 PID: 26407 Comm: rnbd-client.sh Kdump: loaded Not tainted 6.2.0-rc6-roce-flush+ #53
>>>>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
>>>>>> RIP: 0010:__rxe_cleanup+0x13a/0x170 [rdma_rxe]
>>>>>> Code: 45 84 e4 0f 84 5a ff ff ff 48 89 ef e8 5f 18 71 f9 84 c0 75 90 be c8 00 00 00 48 89 ef e8 be 89 1f fa 85 c0 0f 85 7b ff ff ff <0f> 0b 41 bc ea ff ff ff e9 71 ff ff ff e8 84 7f 1f fa e9 d0 fe ff
>>>>>> RSP: 0018:ffffb09880b6f5f0 EFLAGS: 00010246
>>>>>> RAX: 0000000000000000 RBX: ffff99401f15d6a8 RCX: 0000000000000000
>>>>>> RDX: 0000000000000001 RSI: ffffffffbac8234b RDI: 00000000ffffffff
>>>>>> RBP: ffff99401f15d6d0 R08: 0000000000000001 R09: 0000000000000001
>>>>>> R10: 0000000000002d82 R11: 0000000000000000 R12: 0000000000000001
>>>>>> R13: ffff994101eff208 R14: ffffb09880b6f6a0 R15: 00000000fffffe00
>>>>>> FS: 00007fe113904740(0000) GS:ffff99413bc00000(0000) knlGS:0000000000000000
>>>>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>>> CR2: 00007ff6cde656c8 CR3: 000000001f108004 CR4: 00000000001706f0
>>>>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>>>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>>>>> Call Trace:
>>>>>> <TASK>
>>>>>> rxe_dealloc_pd+0x16/0x20 [rdma_rxe]
>>>>>> ib_dealloc_pd_user+0x4b/0x80 [ib_core]
>>>>>> rtrs_ib_dev_put+0x79/0xd0 [rtrs_core]
>>>>>> destroy_con_cq_qp+0x8a/0xa0 [rtrs_client]
>>>>>> init_path+0x1e7/0x9a0 [rtrs_client]
>>>>>> ? __pfx_autoremove_wake_function+0x10/0x10
>>>>>> ? lock_is_held_type+0xd7/0x130
>>>>>> ? rcu_read_lock_sched_held+0x43/0x80
>>>>>> ? pcpu_alloc+0x3dd/0x7d0
>>>>>> ? rtrs_clt_init_stats+0x18/0x40 [rtrs_client]
>>>>>> rtrs_clt_open+0x24f/0x5a0 [rtrs_client]
>>>>>> ? __pfx_rnbd_clt_link_ev+0x10/0x10 [rnbd_client]
>>>>>> rnbd_clt_map_device+0x6a5/0xe10 [rnbd_client]
>>>>>>
>>>>>> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
>>>>>> ---
>>>>>> drivers/infiniband/ulp/rtrs/rtrs-clt.c | 4 ++++
>>>>>> drivers/infiniband/ulp/rtrs/rtrs-clt.h | 1 +
>>>>>> 2 files changed, 5 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
>>>>>> index c2065fc33a56..4c8f42e46e2f 100644
>>>>>> --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
>>>>>> +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
>>>>>> @@ -1664,6 +1664,7 @@ static int create_con_cq_qp(struct rtrs_clt_con *con)
>>>>>> return -ENOMEM;
>>>>>> }
>>>>>> clt_path->s.dev_ref = 1;
>>>>>> + con->has_dev = true;
>>>>>> query_fast_reg_mode(clt_path);
>>>>>> wr_limit = clt_path->s.dev->ib_dev->attrs.max_qp_wr;
>>>>>> /*
>>>>>> @@ -1690,6 +1691,7 @@ static int create_con_cq_qp(struct rtrs_clt_con *con)
>>>>>> wr_limit = clt_path->s.dev->ib_dev->attrs.max_qp_wr;
>>>>>> /* Shared between connections */
>>>>>> clt_path->s.dev_ref++;
>>>>> Without looking in the code, I would expect dev_ref from the line above
>>>>> to perform PD protection.
>>>> Agreed.
>>> Sorry, i didn't get your point. Do you mean something like this:
>>>
>>> + con->has_dev = true;
>>> clt_path->s.dev_ref++;
>> No, my point was that clt_path->s.dev_ref > 0 means that has_dev is
>> equal to true, and dev_ref is supposed to protect from early PD
>> destruction.
>>
>
>> + if (!con->has_dev)
>> + return;
> We have already done such protection VVVV
>
>> if (clt_path->s.dev_ref && !--clt_path->s.dev_ref) { <<< each cleanup will decrease clt_path->s.dev_ref
>> rtrs_ib_dev_put(clt_path->s.dev); <<< when it becomes to 0, PD will be destructed.
>> clt_path->s.dev = NULL;
>
> But they are not equal, clt_path->s.dev_ref could be shared by multiple connections.
> So in the case con[0] successed and con[1] failed(clt_path->s.dev_ref is 1),
> the con[1]'s cleanup path(destroy_con_cq_qp) will destroy PD while conn[0] still associates this PD.
Then what is the appropriate time to call destroy_con_cq_qp for this
scenario?
Otherwise there could be memory leak.
Thanks,
Guoqing
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