Re: [PATCH for-next v2 3/3] RDMA/rtrs: Fix rxe_dealloc_pd warning

[Jinpu Wang]

On Sun, Apr 23, 2023 at 3:27 AM Li Zhijian <lizhijian@xxxxxxxxxxx> wrote:
>
> In current design:
> 1. PD and clt_path->s.dev are shared among connections.
> 2. every con[n]'s cleanup phase will call destroy_con_cq_qp()
> 3. clt_path->s.dev will be always decreased in destroy_con_cq_qp(), and
>    when clt_path->s.dev become zero, it will destroy PD.
> 4. when con[1] failed to create, con[1] will not take clt_path->s.dev,
>    but it try to decreased clt_path->s.dev
>
> So, in case create_cm(con[0]) succeeds but create_cm(con[1])
> fails, destroy_con_cq_qp(con[1]) will be called first which will destory
> the PD while this PD is still taken by con[0].
>
> Here, we refactor the error path of create_cm() and init_conns(), so that
> we do the cleanup in the order they are created.
>
> The warning occurs when destroying RXE PD whose reference count is not
> zero.
> -----------------------------------------------
>  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@xxxxxxxxxxx>
I've tested this version, and it works fine and looks fine.
Ack-by: Jack Wang <jinpu.wang@xxxxxxxxx>
Tested-by: Jack Wang <jinpu.wang@xxxxxxxxx>

Thx!
> ---
> V2: refactor error path instead of introducing a new flag #Leon
> ---
>  drivers/infiniband/ulp/rtrs/rtrs-clt.c | 55 +++++++++++---------------
>  1 file changed, 23 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> index c2065fc33a56..5234be5c6bf8 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> @@ -2039,6 +2039,7 @@ static int rtrs_clt_rdma_cm_handler(struct rdma_cm_id *cm_id,
>         return 0;
>  }
>
> +/* The caller should the do the cleanup in case of error */
>  static int create_cm(struct rtrs_clt_con *con)
>  {
>         struct rtrs_path *s = con->c.path;
> @@ -2061,14 +2062,14 @@ static int create_cm(struct rtrs_clt_con *con)
>         err = rdma_set_reuseaddr(cm_id, 1);
>         if (err != 0) {
>                 rtrs_err(s, "Set address reuse failed, err: %d\n", err);
> -               goto destroy_cm;
> +               return err;
>         }
>         err = rdma_resolve_addr(cm_id, (struct sockaddr *)&clt_path->s.src_addr,
>                                 (struct sockaddr *)&clt_path->s.dst_addr,
>                                 RTRS_CONNECT_TIMEOUT_MS);
>         if (err) {
>                 rtrs_err(s, "Failed to resolve address, err: %d\n", err);
> -               goto destroy_cm;
> +               return err;
>         }
>         /*
>          * Combine connection status and session events. This is needed
> @@ -2083,29 +2084,15 @@ static int create_cm(struct rtrs_clt_con *con)
>                 if (err == 0)
>                         err = -ETIMEDOUT;
>                 /* Timedout or interrupted */
> -               goto errr;
> -       }
> -       if (con->cm_err < 0) {
> -               err = con->cm_err;
> -               goto errr;
> +               return err;
>         }
> -       if (READ_ONCE(clt_path->state) != RTRS_CLT_CONNECTING) {
> +       if (con->cm_err < 0)
> +               return con->cm_err;
> +       if (READ_ONCE(clt_path->state) != RTRS_CLT_CONNECTING)
>                 /* Device removal */
> -               err = -ECONNABORTED;
> -               goto errr;
> -       }
> +               return -ECONNABORTED;
>
>         return 0;
> -
> -errr:
> -       stop_cm(con);
> -       mutex_lock(&con->con_mutex);
> -       destroy_con_cq_qp(con);
> -       mutex_unlock(&con->con_mutex);
> -destroy_cm:
> -       destroy_cm(con);
> -
> -       return err;
>  }
>
>  static void rtrs_clt_path_up(struct rtrs_clt_path *clt_path)
> @@ -2333,7 +2320,7 @@ static void rtrs_clt_close_work(struct work_struct *work)
>  static int init_conns(struct rtrs_clt_path *clt_path)
>  {
>         unsigned int cid;
> -       int err;
> +       int err, i;
>
>         /*
>          * On every new session connections increase reconnect counter
> @@ -2349,10 +2336,8 @@ static int init_conns(struct rtrs_clt_path *clt_path)
>                         goto destroy;
>
>                 err = create_cm(to_clt_con(clt_path->s.con[cid]));
> -               if (err) {
> -                       destroy_con(to_clt_con(clt_path->s.con[cid]));
> +               if (err)
>                         goto destroy;
> -               }
>         }
>         err = alloc_path_reqs(clt_path);
>         if (err)
> @@ -2363,15 +2348,21 @@ static int init_conns(struct rtrs_clt_path *clt_path)
>         return 0;
>
>  destroy:
> -       while (cid--) {
> -               struct rtrs_clt_con *con = to_clt_con(clt_path->s.con[cid]);
> +       /* Make sure we do the cleanup in the order they are created */
> +       for (i = 0; i <= cid; i++) {
> +               struct rtrs_clt_con *con;
>
> -               stop_cm(con);
> +               if (!clt_path->s.con[i])
> +                       break;
>
> -               mutex_lock(&con->con_mutex);
> -               destroy_con_cq_qp(con);
> -               mutex_unlock(&con->con_mutex);
> -               destroy_cm(con);
> +               con = to_clt_con(clt_path->s.con[i]);
> +               if (con->c.cm_id) {
> +                       stop_cm(con);
> +                       mutex_lock(&con->con_mutex);
> +                       destroy_con_cq_qp(con);
> +                       mutex_unlock(&con->con_mutex);
> +                       destroy_cm(con);
> +               }
>                 destroy_con(con);
>         }
>         /*
> --
> 2.29.2
>