[Bug 1340451] [NEW] nfs client hangs when nlockmgr service at rpcbind refuses connection

Marcelo Salhab Brogliato msbrogli at vialink.com.br
Thu Jul 10 22:33:27 UTC 2014


Public bug reported:

Steps to replicate the problem:

1) Install NFS server at nfs-server and export /export/test
2) Install NFS client at nfs-client and mount /export/test from nfs-server
3) Somehow you need to block connections at nlockmgr service in the nfs-server (Connection refused). The results should be like the following:

    nfs-server ~ # rpcinfo -t 127.0.0.1 nlockmgr
    rpcinfo: RPC: Remote system error - Connection refused
    program 100021 is not available

But, nlockmgr have to be listed in your rpcinfo -p:

    nfs-server ~ # rpcinfo -p
    program vers proto   port  service
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100021    3   udp  55320  nlockmgr
    100021    3   tcp  38808  nlockmgr
    100021    4   tcp  38468  nlockmgr
    100021    1   udp    812  nlockmgr
    100021    1   tcp    814  nlockmgr
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100227    2   tcp   2049
    100227    3   tcp   2049
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    4   udp   2049  nfs
    100227    2   udp   2049
    100227    3   udp   2049
    100005    1   udp  50765  mountd
    100005    1   tcp  52776  mountd
    100005    2   udp  42094  mountd
    100005    2   tcp  59107  mountd
    100005    3   udp  57465  mountd
    100005    3   tcp  51252  mountd
    100024    1   udp  42341  status
    100024    1   tcp  33932  status

4) Then, you try to get a lock at any file in nfs-client. Example:
    python
    >>> import fcntl; fp = open('index.html', 'w'); fcntl.flock(fp, fcntl.LOCK_EX)

The client will hang forever and you have to kill -9 your python
process.


nfs-client ~ # lsb_release -rd
Description:	Ubuntu 12.04.4 LTS
Release:	12.04

nfs-client ~ # apt-cache policy nfs-common
nfs-common:
  Installed: 1:1.2.5-3ubuntu3.1
  Candidate: 1:1.2.5-3ubuntu3.1
  Version table:
 *** 1:1.2.5-3ubuntu3.1 0
        500 http://br.archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:1.2.5-3ubuntu3 0
        500 http://br.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages

** Affects: nfs-utils (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1340451

Title:
  nfs client hangs when nlockmgr service at rpcbind refuses connection

Status in “nfs-utils” package in Ubuntu:
  New

Bug description:
  Steps to replicate the problem:

  1) Install NFS server at nfs-server and export /export/test
  2) Install NFS client at nfs-client and mount /export/test from nfs-server
  3) Somehow you need to block connections at nlockmgr service in the nfs-server (Connection refused). The results should be like the following:

      nfs-server ~ # rpcinfo -t 127.0.0.1 nlockmgr
      rpcinfo: RPC: Remote system error - Connection refused
      program 100021 is not available

  But, nlockmgr have to be listed in your rpcinfo -p:

      nfs-server ~ # rpcinfo -p
      program vers proto   port  service
      100000    4   tcp    111  portmapper
      100000    3   tcp    111  portmapper
      100000    2   tcp    111  portmapper
      100000    4   udp    111  portmapper
      100000    3   udp    111  portmapper
      100000    2   udp    111  portmapper
      100021    3   udp  55320  nlockmgr
      100021    3   tcp  38808  nlockmgr
      100021    4   tcp  38468  nlockmgr
      100021    1   udp    812  nlockmgr
      100021    1   tcp    814  nlockmgr
      100003    2   tcp   2049  nfs
      100003    3   tcp   2049  nfs
      100003    4   tcp   2049  nfs
      100227    2   tcp   2049
      100227    3   tcp   2049
      100003    2   udp   2049  nfs
      100003    3   udp   2049  nfs
      100003    4   udp   2049  nfs
      100227    2   udp   2049
      100227    3   udp   2049
      100005    1   udp  50765  mountd
      100005    1   tcp  52776  mountd
      100005    2   udp  42094  mountd
      100005    2   tcp  59107  mountd
      100005    3   udp  57465  mountd
      100005    3   tcp  51252  mountd
      100024    1   udp  42341  status
      100024    1   tcp  33932  status

  4) Then, you try to get a lock at any file in nfs-client. Example:
      python
      >>> import fcntl; fp = open('index.html', 'w'); fcntl.flock(fp, fcntl.LOCK_EX)

  The client will hang forever and you have to kill -9 your python
  process.

  
  nfs-client ~ # lsb_release -rd
  Description:	Ubuntu 12.04.4 LTS
  Release:	12.04

  nfs-client ~ # apt-cache policy nfs-common
  nfs-common:
    Installed: 1:1.2.5-3ubuntu3.1
    Candidate: 1:1.2.5-3ubuntu3.1
    Version table:
   *** 1:1.2.5-3ubuntu3.1 0
          500 http://br.archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       1:1.2.5-3ubuntu3 0
          500 http://br.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages

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