linux-kernel - Re: detecting kernel mem leak

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Message-ID: <84144f020804290546h666983aci77fbb08eb507e777@mail.gmail.com>
Date:	Tue, 29 Apr 2008 15:46:42 +0300
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	sancelot@...e.fr
Cc:	linux-kernel@...r.kernel.org,
	"Christoph Lameter" <clameter@....com>
Subject: Re: detecting kernel mem leak

On Tue, Apr 29, 2008 at 12:41 PM,  <sancelot@...e.fr> wrote:
>  I noticed the memory was growing without doing anything in my system ....after
>  some investigations , it looks like some kernel components may be involved in
>  this problem.
>
>  I would like to know if there is a way to monitor activity of memory (de)alloc
>  of the kernel in order to target which partof the system/kernel could do this..?

You can do

 cat /proc/meminfo | grep Slab

and if that grows too much over time you can do

  cat /proc/slabinfo

or use a tool such as slabtop to see where the memory is going. If the
memory is being leaked in the kmalloc caches, you can use
CONFIG_DEBUG_SLAB_LEAK which part of the kernel is doing all those
allocations (not really suitable for production machines).

Also remember to check that Active + Inactive + Buffers + Cached is
roughly the same size as MemTotal - MemFree; otherwise your kernel
might be leaking full pages.

Christoph, I suppose there's some option to
Documentation/vm/slabinfo.c that provides similar output to
CONFIG_DEBUG_SLAB_LEAK for SLUB?

                                Pekka
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