lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <f85cdaaa-b1d6-bc89-e963-8b611ae3667d@fujitsu.com>
Date:   Thu, 13 Apr 2023 08:12:15 +0000
From:   "Zhijian Li (Fujitsu)" <lizhijian@...itsu.com>
To:     Guoqing Jiang <guoqing.jiang@...ux.dev>,
        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



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.

> Then what is the appropriate time to call destroy_con_cq_qp for this scenario?
> Otherwise there could be memory leak.

we must ensure QP in con[0] is closed before destroying the PD.
Currently destroy_con_cq_qp() subroutine will close the opened QP first.


Thanks


> 
>>>>>>> }
>>>>>>>
>>>>>>> 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

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ