[Bug 1047566] Re: Memory leaks when using NFS

[Andrew Martin]

I am also experiencing this bug on 12.04 amd64 with 3.2.0-26-generic and
3.2.0-27-generic. I am running an NFS server and a Samba server. Similar
to the original reporter I am serving many small files from an ext4
partition to a number of NFS clients. I believe they are almost
exclusively using NFSv3. This server has 6GB of RAM, which
idr_layer_cache will consume entirely until the OOM killer is invoked.
The only workaround I have found so far is rebooting the server. What
other debug information can I provide to help resolve this bug?

Attached is the output of nfsstat.

** Attachment added: "output of 'nfsstat'"
   https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1047566/+attachment/3312460/+files/nfsstat.log

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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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