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Date:   Tue, 11 Apr 2023 15:26:51 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     "Zhijian Li (Fujitsu)" <lizhijian@fujitsu.com>
Cc:     Guoqing Jiang <guoqing.jiang@linux.dev>,
        "haris.iqbal@ionos.com" <haris.iqbal@ionos.com>,
        "jinpu.wang@ionos.com" <jinpu.wang@ionos.com>,
        "jgg@ziepe.ca" <jgg@ziepe.ca>,
        "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH for-next 2/3] RDMA/rtrs: Fix rxe_dealloc_pd warning
Message-ID: <20230411122651.GV182481@unreal>
References: <1681108984-2-1-git-send-email-lizhijian@fujitsu.com>
 <1681108984-2-3-git-send-email-lizhijian@fujitsu.com>
 <20230410120809.GN182481@unreal>
 <0d9c57db-bca3-adb4-71fd-7362e4842917@linux.dev>
 <85323eb2-cfc7-d1b8-3a75-3fa63dde29db@fujitsu.com>
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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+
> >>> ?????????????????????????????????????????? |
> >>> ?? 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?????????? |
> >>> }
> >>>
> >>> 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@fujitsu.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.

Thanks

> 
> 
> 
> Thanks
> Zhijian
> 
> > 
> > Thanks,
> > Guoqing