> On Feb 19, 2021, at 1:01 PM, Timo Rothenpieler <timo@xxxxxxxxxxxxxxxx> wrote: > > On 19.02.2021 18:48, Chuck Lever wrote: >>> On Feb 19, 2021, at 12:38 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote: >>> >>> On Thu, Feb 18, 2021 at 3:22 PM Timo Rothenpieler <timo@xxxxxxxxxxxxxxxx> wrote: >>>> >>>> On 18.02.2021 19:30, Olga Kornievskaia wrote: >>>>> Thank you for getting tracepoints from a busy server but can you get >>>>> more? As suspected, the server is having issues sending the callback. >>>>> I'm not sure why. Any chance to turn on the server's sunrpc >>>>> tracespoints, probably both sunrpc and rdmas tracepoints, I wonder if >>>>> we can any more info about why it's failing? >>>> >>>> I isolated out two of the machines on that cluster now, one acting as >>>> NFS server from an ext4 mount, the other is the same client as before. >>>> That way I managed to capture a trace and ibdump of an entire cycle: >>>> mount + successful copy + 5 minutes later a copy that got stuck >>>> >>>> Next to no noise happened during those traces, you can find them attached. >>>> >>>> Another observation made due to this: unmount and re-mounting the NFS >>>> share also gets it back into working condition for a while, no reboot >>>> necessary. >>>> During this trace, I got "lucky", and after just 5 minutes of waiting, >>>> it got stuck. >>>> >>>> Before that, I had a run of mount + trying to copy every 5 minutes where >>>> it ran for 45 minutes without getting stuck. At which point I decided to >>>> remount once more. >>> >>> Timo, thank you for gathering the debug info. >>> >>> Chuck, I need your help. Why would the server lose a callback channel? >>> >>> <...>-1461944 [001] 2076465.200151: rpc_request: >>> task:57752@6 nfs4_cbv1 CB_OFFLOAD (async) >>> <...>-1461944 [001] 2076465.200151: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE status=0 action=call_reserve >>> <...>-1461944 [001] 2076465.200154: xprt_reserve: >>> task:57752@6 xid=0x00a0aaf9 >>> <...>-1461944 [001] 2076465.200155: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE status=0 action=call_reserveresult >>> <...>-1461944 [001] 2076465.200156: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE status=0 action=call_refresh >>> <...>-1461944 [001] 2076465.200163: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE status=0 action=call_refreshresult >>> <...>-1461944 [001] 2076465.200163: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE status=0 action=call_allocate >>> <...>-1461944 [001] 2076465.200168: rpc_buf_alloc: >>> task:57752@6 callsize=548 recvsize=104 status=0 >>> <...>-1461944 [001] 2076465.200168: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE status=0 action=call_encode >>> <...>-1461944 [001] 2076465.200173: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE|NEED_XMIT|NEED_RECV status=0 >>> action=call_connect >>> <...>-1461944 [001] 2076465.200174: rpc_call_rpcerror: >>> task:57752@6 tk_status=-107 rpc_status=-107 >>> <...>-1461944 [001] 2076465.200174: rpc_task_run_action: >>> task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT >>> runstate=RUNNING|ACTIVE|NEED_XMIT|NEED_RECV status=-107 >>> action=rpc_exit_task >>> >>> It's reporting ENOTCON. I'm not really sure if this is related to copy >>> offload but more perhaps doing callbacks over RDMA/IB. >> If the client is awaiting a COPY notification callback, I can see why >> a lost CB channel would cause the client to wait indefinitely. >> The copy mechanism has to deal with this contingency... Perhaps the >> server could force a disconnect so that the client and server have an >> opportunity to re-establish the callback channel. <shrug> >> In any event, the trace log above shows nothing more than "hey, it's >> not working." Are there any rpcrdma trace events we can look at to >> determine why the backchannel is getting lost? > > The trace log attached to my previous mail has it enabled, along with nfsd and sunrpc. > I'm attaching the two files again here. Thanks, Timo. The first CB_OFFLOAD callback succeeds: 2076155.216687: nfsd_cb_work: addr=10.110.10.252:0 client 602eb645:daa037ae procedure=CB_OFFLOAD 2076155.216704: rpc_request: task:57746@6 nfs4_cbv1 CB_OFFLOAD (async) 2076155.216975: rpc_stats_latency: task:57746@6 xid=0xff9faaf9 nfs4_cbv1 CB_OFFLOAD backlog=33 rtt=195 execute=282 2076155.216977: nfsd_cb_done: addr=10.110.10.252:0 client 602eb645:daa037ae status=0 About 305 seconds later, the autodisconnect timer fires. I'm not sure if this is the backchannel transport, but it looks suspicious: 2076460.314954: xprt_disconnect_auto: peer=[10.110.10.252]:0 state=LOCKED|CONNECTED|BOUND 2076460.314957: xprt_disconnect_done: peer=[10.110.10.252]:0 state=LOCKED|CONNECTED|BOUND The next CB_OFFLOAD callback fails because the xprt has been marked "disconnected" and the request's NOCONNECT flag is set. 2076465.200136: nfsd_cb_work: addr=10.110.10.252:0 client 602eb645:daa037ae procedure=CB_OFFLOAD 2076465.200151: rpc_request: task:57752@6 nfs4_cbv1 CB_OFFLOAD (async) 2076465.200168: rpc_task_run_action: task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT runstate=RUNNING|ACTIVE status=0 action=call_encode 2076465.200173: rpc_task_run_action: task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT runstate=RUNNING|ACTIVE|NEED_XMIT|NEED_RECV status=0 action=call_connect 2076465.200174: rpc_call_rpcerror: task:57752@6 tk_status=-107 rpc_status=-107 2076465.200174: rpc_task_run_action: task:57752@6 flags=ASYNC|DYNAMIC|SOFT|NOCONNECT runstate=RUNNING|ACTIVE|NEED_XMIT|NEED_RECV status=-107 action=rpc_exit_task 2076465.200179: nfsd_cb_done: addr=10.110.10.252:0 client 602eb645:daa037ae status=-107 2076465.200180: nfsd_cb_state: addr=10.110.10.252:0 client 602eb645:daa037ae state=FAULT Perhaps RPC clients for NFSv4.1+ callback should be created with the RPC_CLNT_CREATE_NO_IDLE_TIMEOUT flag. -- Chuck Lever
