Linux memory leak?

W Bauske wsb at
Thu Feb 28 16:51:05 EST 2002

Josip Loncaric wrote:
> On our heterogeneous cluster, we run Red Hat 7.2 updated to stock i686
> Linux kernels 2.4.9-21 or 2.4.9-21smp.  Sometimes (e.g. after 14 days of
> normal operation) our nodes report unusually high memory usage even
> without any user processes active.  This can happen on both single CPU
> and on dual CPU machines, and it used to happen with previous 2.4
> kernels.  Here is an example:
> # free
>              total       used       free     shared    buffers
> cached
> Mem:        512444     449196      63248          0      70164
> 76332
> -/+ buffers/cache:     302700     209744
> Swap:      1060272     285492     774780
> If I add up all RSS numbers reported by 'ps -e v' I get only about
> 20,500 KB, and yet this dual CPU system reports 302,700 KB RAM used
> (without even counting buffers or cache).  Apparently, only 'reboot' can
> recover the missing 282,200 KB.  Any ideas on tracking down where the
> missing memory went?

Write a trivial program that allocates lots of memory and touches
it by writing something into it. Then execute and allocate, say
80-90% of physical memory and see if the memory is really taken or not.
If it allocates, then there's probably nothing of great concern.

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