NFSv4 clientid was expired suddenly due to use same hostname on several NFS clients

Issue

• NFS server returned NFS4ERR_BADSESSION suddenly, but the GETATTR call just before that was successful.

 221402 17:58:28.006327  192.168.122.73 → 192.168.122.72  NFS 258 V4 Call GETATTR FH: 0x9a4cedf5
 221403 17:58:28.006409  192.168.122.72 → 192.168.122.73  NFS 310 V4 Reply (Call In 221402) GETATTR
 221405 17:58:29.176280  192.168.122.73 → 192.168.122.72  NFS 246 V4 Call GETATTR FH: 0xa202f392
 221406 17:58:29.176312  192.168.122.72 → 192.168.122.73  NFS 114 V4 Reply (Call In 221405) SEQUENCE Status: NFS4ERR_BADSESSION
 221408 17:58:29.176602  192.168.122.73 → 192.168.122.72  NFS 170 V4 Call DESTROY_SESSION
 221409 17:58:29.176622  192.168.122.72 → 192.168.122.73  NFS 114 V4 Reply (Call In 221408) DESTROY_SESSION Status: NFS4ERR_BADSESSION
 221410 17:58:29.176769  192.168.122.73 → 192.168.122.72  NFS 266 V4 Call CREATE_SESSION
 221411 17:58:29.176797  192.168.122.72 → 192.168.122.73  NFS 114 V4 Reply (Call In 221410) CREATE_SESSION Status: NFS4ERR_STALE_CLIENTID
 221412 17:58:29.176991  192.168.122.73 → 192.168.122.72  NFS 306 V4 Call EXCHANGE_ID
 221413 17:58:29.177018  192.168.122.72 → 192.168.122.73  NFS 170 V4 Reply (Call In 221412) EXCHANGE_ID
 221414 17:58:29.177176  192.168.122.73 → 192.168.122.72  NFS 266 V4 Call CREATE_SESSION
 221416 17:58:30.166895  192.168.122.72 → 192.168.122.73  NFS 194 V4 Reply (Call In 221414) CREATE_SESSION
 221417 17:58:30.167092  192.168.122.73 → 192.168.122.72  NFS 202 V4 Call PUTROOTFH | GETATTR
 221419 17:58:30.167135  192.168.122.72 → 192.168.122.73  NFS 182 V4 Reply (Call In 221417) PUTROOTFH | GETATTR
 221420 17:58:30.167473  192.168.122.73 → 192.168.122.72  NFS 318 V4 Call OPEN DH: 0x9a4cedf5/
 221421 17:58:30.167517  192.168.122.72 → 192.168.122.73  NFS 166 V4 Reply (Call In 221420) OPEN Status: NFS4ERR_NO_GRACE
 221422 17:58:30.167758  192.168.122.73 → 192.168.122.72  NFS 194 V4 Call RECLAIM_COMPLETE
 221424 17:58:30.243923  192.168.122.72 → 192.168.122.73  NFS 158 V4 Reply (Call In 221422) RECLAIM_COMPLETE
 221425 17:58:30.244109  192.168.122.73 → 192.168.122.72  NFS 326 V4 Call OPEN DH: 0x9a4cedf5/
 221427 17:58:30.244178  192.168.122.72 → 192.168.122.73  NFS 386 V4 Reply (Call In 221425) OPEN StateID: 0x0ad9

• And CREATE_SESSION was failed with NFS4ERR_STALE_CLIENTID. The clientid was expired so EXCHANGE_ID was needed to get new clientid.