[Bug 1047566] Re: Memory leaks when using NFS

[Esa Ollitervo]

I've recently been wondering why my kvm server runs out of memory when I
try to run minecraft server on one virtual machine. It looks like the
problem is caused by this bug. I'm now running 3.2.0-36 on the host and
virtual machines but I still cannot run minecraft on the virtual machine
without idr_layer_cache growing endlessly until the server runs out of
memory.

The server is running stable if I don't try to run minecraft. If I do it
usually runs out of memory in a few hours.

On the server I have six virtual machines running.
The server has 18GB memory and virtual machines use only 8GB.
I have exported home directories from the server to virtual machines using NFSv3.
The filesystem for home directories is formatted as XFS.

 On the minecraft virtual machine I have 2GB memory and a lvm partition for minecraft and other stuff.
The lvm partition resides on the same physical disk as the home directories.

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https://bugs.launchpad.net/bugs/1047566

Title:
  Memory leaks when using NFS

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

Bug description:
  When using Ubuntu Server 12.04 with or without the latest updates
  (kernels 3.2.0-23 and 3.2.0-29, x86_64) as an NFS server with fairly
  heavy reading activity from clients (no writing), from a volume with a
  lot of small files, split into many subdirectories (with about 5-10
  files or subdirectories per directory, in a tree-like structure not
  unlike that of Squid proxy), available memory is quickly exhausted,
  however no single process shows that much memory being used, nor does
  the "buffers" or "cached" in "free" command output. The server
  eventually runs out of memory and crashes.

  slabtop shows that majority of memory is being used by idr_layer_cache
  (3.6G on a sever with 4G of RAM shortly before the kernel started
  killing processes and eventually crashed).

  The filesystem being shared is ext4. Clients (also the same version of
  Ubuntu Server) mount the volume in read-only mode, with default
  options.

  P.S. Also tried i386 version, with the same result.

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