[Bug 879334] Re: nfsd from nfs-kernel-server very slow and system load from 25%-100% from nfsd

[Sven Rudolph]

Same here.
NFSv4 mounted home dirs (from a Ubuntu 12.04 LTS NFSv4 server) become very slow. Eventually the client machine freezes completely -> reset button.
Using Opensuse 12.2 as NFSv4 client produces no problems at all.
This is reproducable.

Same on some of our servers with NFSv4 mounted directories. All Ubuntu 12.04 LTS, NFSv4 servers and clients.
Frequent messages in /var/log/syslog:
[...]
Jan 25 11:49:39 xxx kernel: [ 8996.289241] Call Trace:
Jan 25 11:49:39 xxx kernel: [ 8996.289246]  [<ffffffff81659ebf>] schedule+0x3f/0x60
Jan 25 11:49:39 xxx kernel: [ 8996.289249]  [<ffffffff8165acc7>] __mutex_lock_slowpath+0xd7/0x150
Jan 25 11:49:39 xxx kernel: [ 8996.289253]  [<ffffffff8165a8da>] mutex_lock+0x2a/0x50
Jan 25 11:49:39 xxx kernel: [ 8996.289256]  [<ffffffff81186404>] do_last+0x2b4/0x730
Jan 25 11:49:39 xxx kernel: [ 8996.289260]  [<ffffffff81187c21>] path_openat+0xd1/0x3f0
Jan 25 11:49:39 xxx kernel: [ 8996.289263]  [<ffffffff81183565>] ? putname+0x35/0x50
Jan 25 11:49:39 xxx kernel: [ 8996.289266]  [<ffffffff81187fc3>] ? user_path_at_empty+0x63/0xa0
Jan 25 11:49:39 xxx kernel: [ 8996.289275]  [<ffffffffa01337db>] ? nfs_attribute_cache_expired+0x1b/0x70 [nfs]
Jan 25 11:49:39 xxx kernel: [ 8996.289279]  [<ffffffff81188062>] do_filp_open+0x42/0xa0
Jan 25 11:49:39 xxx kernel: [ 8996.289284]  [<ffffffff81319c11>] ? strncpy_from_user+0x31/0x40
Jan 25 11:49:39 xxx kernel: [ 8996.289287]  [<ffffffff811833aa>] ? do_getname+0x10a/0x180
Jan 25 11:49:39 xxx kernel: [ 8996.289291]  [<ffffffff8165bdce>] ? _raw_spin_lock+0xe/0x20
Jan 25 11:49:39 xxx kernel: [ 8996.289294]  [<ffffffff81195377>] ? alloc_fd+0xf7/0x150
Jan 25 11:49:39 xxx kernel: [ 8996.289298]  [<ffffffff81177688>] do_sys_open+0xf8/0x240
Jan 25 11:49:39 xxx kernel: [ 8996.289301]  [<ffffffff811777f0>] sys_open+0x20/0x30
Jan 25 11:49:39 xxx kernel: [ 8996.289304]  [<ffffffff816643c2>] system_call_fastpath+0x16/0x1b
[...]

Eventually the servers which act as NFS clients freeze completely -> remote reset. (It's just a test system).
This is reproducable.
Needless to say, that this disqualifies Ubuntu 12.04 LTS as an NFS client.

A fix of this bug would be highly appreciated!

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https://bugs.launchpad.net/bugs/879334

Title:
  nfsd from nfs-kernel-server very slow and system load from 25%-100%
  from nfsd

Status in “linux” package in Ubuntu:
  Incomplete
Status in “nfs-utils” package in Ubuntu:
  Confirmed
Status in “linux” package in Debian:
  Incomplete

Bug description:
  I have a diskless ubuntu 10.10 machine which I boot regularly using
  pxe-boot from another ubuntu machine where I have the root filesystem
  of the diskless machine exported over nfs.

  I set it up about a year ago using 10.10. In the mean while the server
  machine got upgraded to 11.04 and as of yesterday to 11.10.

  After the upgrade to 11.10 the diskless machine is dead slow (most of
  the times it wont even boot completely) and the load on the server
  machine is high (25%-100% as shown from top). If in the middle of the
  diskless computer booting I do a restart of the nfs server, the client
  computer proceeds with the boot a bit more and then it gets stuck
  again. I have to restart and nfs-server 3-4 times in order to get the
  gdm login screen at the client machine

  ProblemType: Bug
  DistroRelease: Ubuntu 11.10
  Package: nfs-kernel-server 1:1.2.4-1ubuntu2
  ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
  Uname: Linux 3.0.0-12-generic i686
  ApportVersion: 1.23-0ubuntu3
  Architecture: i386
  Date: Fri Oct 21 12:53:02 2011
  ProcEnviron:
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: nfs-utils
  UpgradeStatus: Upgraded to oneiric on 2011-10-20 (1 days ago)

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