NFS mount during startup causes excessive memory usage

[GeniusDex]

I just installed Kubuntu 11.10 with kernel 3.0.0.12.14 and nfs-common 1:1.2.4-1ubuntu2 . I added a line to fstab (see below) to mount my NFS filesystem automatically on boot. Now, when rebooting the memory usage of my system keeps increasing indefinitely. In 15 minutes i went from 1.0GB to 2.2GB of usage while only using firefox (using 150MB) and some terminals. The running processes did not significantly consume more memory during that 15 minutes, so it must be used in the kernel.

When i unmount the NFS filesystem the memory usage of the whole system drops back to the original 1.0GB. Re-mounting it from user space does not start the increase of memory usage again. In both cases (original mount and re-mount) using the NFS filesystem works just fine. I'd expect the memory usage to stay low as well, regardless of how the filesystem is mounted.

The fstab line is:
elephant.local:/data /data nfs defaults,user 0 0

The server-side options for NFS are: rw,no_subtree_check,async

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: nfs-common 1:1.2.4-1ubuntu2
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
Date: Sun Oct 30 19:09:11 2011
InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
ProcEnviron:
 LANGUAGE=
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: nfs-utils
UpgradeStatus: No upgrade log present (probably fresh install)

[GeniusDex (geniusdex)]

Got some more info after a few days of use.

The memory usage increase always takes up about 1.1 GB and then the increase stops. It does not matter whether i first mount it using auto-mounting at boot or do it via a user-script in startup; in both cases, the memory usage increases. While the memory is increasing i cannot unmount the device:

umount.nfs: /data: device is busy
umount.nfs: /data: device is busy

Once it's done increasing, i can unmount and re-mount the filesystem and the memory usage does not increase.