[2.2.13] memory leak in NFS if a sever goes away?

[2.2.13] memory leak in NFS if a sever goes away?

[Florian Weimer]

We've received a hard disk for post-mortem analysis because of a
strange hole of several months in the system logs, and it seems the
system's syslogd was killed by the VM subsystem during an OOM
situation.

The problems seem to begin at the following syslog event:

   kernel: nfs: server sun not responding, still trying

Periodically (every quarter of an hour), the following messages appear:

   kernel: nfs: task 111 can't get a request slot

(The task number is monotonically increasing.)

This goes on for about two days, after which the VM subsystem starts
killing processes (kdm first, then several times the X server, and
finally syslogd itself).

Are there some known issues with 2.2.13, for example, a memory leak in
the NFS code which is triggered in this specific situation?

(The kernel seems to have some SuSE-specific patches, for example, the
X server is sent the TERM signal, not the KILL signal on OOM.  Perhaps
I should ask the SuSE folks if there were any NFS peculiarities in
their 2.2.13 version. :-/)

-- 
Florian Weimer 	                  Florian.Weimer@RUS.Uni-Stuttgart.DE
University of Stuttgart           http://cert.uni-stuttgart.de/
RUS-CERT                          +49-711-685-5973/fax +49-711-685-5898

Re: [2.2.13] memory leak in NFS if a sever goes away?

[Matthias Andree]

Florian Weimer schrieb am Dienstag, den 31. Juli 2001:

> We've received a hard disk for post-mortem analysis because of a
> strange hole of several months in the system logs, and it seems the
> system's syslogd was killed by the VM subsystem during an OOM
> situation.

If it's crucial, list it in inittab.

> Are there some known issues with 2.2.13, for example, a memory leak in
> the NFS code which is triggered in this specific situation?

There are known security threats in 2.2.x which have been fixed in
2.2.16, and there have been VM fixes in a later version, and further
minor but numerable security fixes in 2.2.19.

Update to 2.2.19. Don't bother analyzing 2.2.13, no-one fixes that
nowadays unless the problem persists in 2.2.19.

Re: [2.2.13] memory leak in NFS if a sever goes away?

[Florian Weimer]

Matthias Andree <matthias.andree@stud.uni-dortmund.de> writes:

> > Are there some known issues with 2.2.13, for example, a memory leak in
> > the NFS code which is triggered in this specific situation?
> 
> There are known security threats in 2.2.x which have been fixed in
> 2.2.16, and there have been VM fixes in a later version, and further
> minor but numerable security fixes in 2.2.19.

The system has already been installed from scratch, using a more
recent kernel version.  I agree that the kind of information I'm
looking for is not crucial for running a current Linux kernel, but we
were specifically asked to explain what has happened to the machine
(and we do have satisfactory explanations for other strange things
which were obsvered---no it wasn't hacked ;-), but this problem still
remains a bit mysterious.  I just wanted to make sure that the problem
described in my first posting is not a once well-known issue with
2.2.13 or other 2.2.x kernels, and that I didn't miss an obvious
explanation.

-- 
Florian Weimer 	                  Florian.Weimer@RUS.Uni-Stuttgart.DE
University of Stuttgart           http://cert.uni-stuttgart.de/
RUS-CERT                          +49-711-685-5973/fax +49-711-685-5898