Hi experts, I create VFS export in ganesha server. My client is ubuntu-12.04 and its kernel is 3.2.0. I tried to read a file in the client, such as root@vagrant:~# cat /mnt/vfs/1.txt cat: /mnt/vfs/1.txt: Input/output error Below is the kernel log. It seems that print_overflow_msg() is called. [ 86.107842] RPC: 15 call_start nfs4 proc OPEN (async) [ 86.107843] RPC: 15 call_reserve (status 0) [ 86.107846] RPC: 15 reserved req ffff88003ccf9e00 xid 26da5a05 [ 86.107848] RPC: wake_up_next(ffff88003a205990 "xprt_sending") [ 86.107850] RPC: 15 call_reserveresult (status 0) [ 86.107852] RPC: 15 call_refresh (status 0) [ 86.107855] RPC: 15 refreshing UNIX cred ffff880039b35c00 [ 86.107856] RPC: 15 call_refreshresult (status 0) [ 86.107858] RPC: 15 call_allocate (status 0) [ 86.107860] RPC: 15 allocated buffer of size 2536 at ffff88003b3d9000 [ 86.107861] RPC: 15 call_bind (status 0) [ 86.107863] RPC: 15 call_connect xprt ffff88003a205800 is connected [ 86.107864] RPC: 15 call_transmit (status 0) [ 86.107865] RPC: 15 xprt_prepare_transmit [ 86.107866] RPC: 15 rpc_xdr_encode (status 0) [ 86.107867] RPC: 15 marshaling UNIX cred ffff880039b35c00 [ 86.107869] RPC: 15 using AUTH_UNIX cred ffff880039b35c00 to wrap rpc data [ 86.107870] encode_compound: tag= [ 86.107872] encode_sequence: sessionid=2:1564646257:2:0 seqid=12 slotid=0 max_slotid=0 cache_this=1 [ 86.107874] RPC: 15 xprt_transmit(268) [ 86.107980] RPC: xs_tcp_send_request(268) = 268 [ 86.107981] RPC: 15 xmit complete [ 86.107983] RPC: 15 sleep_on(queue "xprt_pending" time 4294912605) [ 86.107985] RPC: 15 added to queue ffff88003a205a58 "xprt_pending" [ 86.107986] RPC: 15 setting alarm for 60000 ms [ 86.107988] RPC: wake_up_next(ffff88003a205990 "xprt_sending") [ 86.112120] RPC: xs_tcp_data_ready... [ 86.112123] RPC: xs_tcp_data_recv started [ 86.112125] RPC: reading TCP record fragment of length 536 [ 86.112126] RPC: reading XID (4 bytes) [ 86.112128] RPC: reading reply for XID 26da5a05 [ 86.112129] RPC: reading CALL/REPLY flag (4 bytes) [ 86.112131] RPC: read reply XID 26da5a05 [ 86.112132] RPC: XID 26da5a05 read 528 bytes [ 86.112134] RPC: xprt = ffff88003a205800, tcp_copied = 536, tcp_offset = 536, tcp_reclen = 536 [ 86.112136] RPC: 15 xid 26da5a05 complete (536 bytes received) [ 86.112138] RPC: 15 __rpc_wake_up_task (now 4294912606) [ 86.112139] RPC: 15 disabling timer [ 86.112141] RPC: 15 removed from queue ffff88003a205a58 "xprt_pending" [ 86.112145] RPC: __rpc_wake_up_task done [ 86.112146] RPC: xs_tcp_data_recv done [ 86.113873] RPC: 15 __rpc_execute flags=0x881 [ 86.113875] RPC: 15 call_status (status 536) [ 86.113877] RPC: 15 call_decode (status 536) [ 86.113879] RPC: 15 validating UNIX cred ffff880039b35c00 [ 86.113881] RPC: 15 using AUTH_UNIX cred ffff880039b35c00 to unwrap rpc data [ 86.113886] nfs: decode_opaque_inline: prematurely hit end of receive buffer. Remaining buffer length is 87 words. [ 86.113888] RPC: 15 call_decode result -5 [ 86.113890] nfs41_sequence_done: Error 0 free the slot [ 86.113891] nfs4_free_slot: free_slotid 0 highest_used_slotid -1 [ 86.113893] RPC: wake_up_next(ffff88003cdf1860 "ForeChannel Slot table") [ 86.113894] RPC: 15 return 0, status -5 [ 86.113895] RPC: 15 release task [ 86.113898] RPC: freeing buffer of size 2536 at ffff88003b3d9000 [ 86.113900] RPC: 15 release request ffff88003ccf9e00 [ 86.113901] RPC: wake_up_next(ffff88003a205b20 "xprt_backlog") [ 86.113903] RPC: rpc_release_client(ffff88003bd98a00) [ 86.113909] RPC: 15 freeing task [ 86.113914] NFS: dentry_delete(//1.txt, c) It seems only happen on Linux kernel 3.x rather than 4.x. I debug the issue, I found the issue is in the xdr_open_delegation4(). When the delegation_type is OPEN_DELEGATE_NONE_EXT, the problem happened. If it is OPEN_DELEGATE_NONE, it the problem is gone. I don't know what's the difference between them. Is this a ganesha bug or old Linux kernel bug? Thanks, Marvin