[Bug 1047566] Re: Memory leaks when using NFS

[Daniel Jarman]

Also confirmed on 12.04.2 server

upgrading to the quantal release kernel 3.5 didn't fix the problem:

uname -a
3.5.0-23-generic #35~precise1-Ubuntu SMP Fri Jan 25 17:13:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

I have tried both NFSv3 & v4 mounts with the same result. When the
problem occurs I have observed excessive io from jdb2 with slabtop
reporting idr_layer_cache continuously growing. /proc/meminfo also shows
SUnreclaim growing until the system crashes confirming that this is a
leak...

Is changing to the mainline kernel the only proposed fix for this issue?

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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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