[Bug 1047566] Re: Memory leaks when using NFS

[Anders Hall]

We have seen this for many months now. The only workaround we have found
is, as mentioned, to reboot when memory is reaching a crash.

The release below did not work.

"Processes that open and close multiple files may end up setting this
    oo_last_closed_stid without freeing what was previously pointed to.
    This can result in a major leak, visible for example by watching the
    nfsd4_stateids line of /proc/slabinfo"

This micro machine on ec2 will soon crash. We don't have that many files
on nfs and mostly read from it. We also load a few large files when
processes start (700 mb or so, read once).

uname -a
Linux ip-10-48-5-128 3.2.0-36-virtual #57-Ubuntu SMP Tue Jan 8 22:04:49 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

 OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
855315 855315 100%    0.53K  57021       15    456168K idr_layer_cache
 55040  55040 100%    0.02K    215      256       860K kmalloc-16

Is there any way to solve this on the client side by changing how
read/write operations are done?

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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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