lkml.org 
[lkml]   [2004]   [Oct]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Gigantic memory leak in linux-2.6.[789]!
On Fri, 22 Oct 2004, [ISO-8859-15] Kristian Sørensen wrote:

> Richard B. Johnson wrote:
>> On Fri, 22 Oct 2004, Kasper Sandberg wrote:
>>
>>> On Fri, 2004-10-22 at 16:13 +0200, Kristian Sørensen wrote:
>>>
>>>> Hi all!
>>>>
>>>> After some more testing after the previous post of the OOPS in
>>>> generic_delete_inode, we have now found a gigantic memory leak in Linux
>>>> 2.6.
>>>> [789]. The scenario is the same:
>>>>
>>>> File system: EXT3
>>>> Unpack and delete linux-2.6.8.1.tar.bz2 with this Bash while loop:
>>>>
>>>> let "i = 0"
>>>> while [ "$i" -lt 10 ]; do
>>>> tar jxf linux-2.6.8.1.tar.bz2;
>>>> rm -fr linux-2.6.8.1;
>>>> let "i = i + 1"
>>>> done
>>>>
>>>> When the loop has completed, the system use 124 MB memory more _each_
>>>> time....
>>>> so it is pretty easy to make a denial-of-service attack :-(
>>
>>
>>
>> Do something like this with your favorite kernel version.....
>>
>> while true ; do tar -xzf linux-2.6.9.tar.gz ; rm -rf linux-2.6.9 ; vmstat ;
>> done
>>
>> You can watch this for as long as you want. If there is no other
>> activity, the values reported by vmstat remain, on the average, stable.
>> If you throw in a `sync` command, the values rapidly converge to
>> little memory usage as the disk-data gets flused to disk.
> The problem is, that the free memory reported by vmstat is decresing by 124mb
> for each 10-iterations....
>
> The allocated memory does not get freed even if the system has been left
> alone for three hours!
>

Yes. So? Why would it be freed? It's left how it was until it
is needed. Freeing it would waste CPU cycles.

This cannot be a problem unless you are inventing some sort
of hot-swap memory thing. If so, you need to make a module that
tells the kernel memory manager to free everything so you
can remove and replace the RAM.


>
> Cheers, Kristian.


>
> --
> Kristian Sørensen
> - The Umbrella Project
> http://umbrella.sourceforge.net
>
> E-mail: ipqw@users.sf.net, Phone: +45 29723816
>

Cheers,
Dick Johnson
Penguin : Linux version 2.6.9 on an i686 machine (5537.79 GrumpyMips).
98.36% of all statistics are fiction.
\
 
 \ /
  Last update: 2005-03-22 14:07    [W:0.074 / U:21.960 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site