[OpenAFS] Can't get this going on Coraid CLN22 (Debian).
Ed L. Cashin
Fri, 30 Mar 2007 15:36:16 -0400
On Thu, Mar 29, 2007 at 08:00:49PM -0500, Tony Shadwick wrote:
> I won't call it "fixed", but with much help from the guys in #openafs,
> we did get things working.
> The stack size is set to 8192. We had to change that to unlimited,
> then things started working, so ulimit -s unlimited.
> Ed, if you see this...any thoughts on what might cause this?
Well, an OpenAFS process probably has a large array or similar data
structure on its stack (usually a function-local variable in a C
The ulimit is a system setting that prevents processes from using a
large amount of memory for stack space. On the CLN or other server,
especially one without swap space, that limit could help to prevent a
greedy user process from consuming the RAM that the system needs to
The setting is a trade off. By removing the limit, you give processes
greater freedom while losing the stability that the limit can provide.
In the end, user processes can usually perform a denial of service
attack somehow on the local host, whether it's with the notorious
"fork bomb" or some more insidious exploitation of a weakness in the
kernel. Still, multi-level security is a good policy.
> I've been instructed to file a bug report on openafs-bugs, and to debian
> regarding the package, as the /etc/init.d/openafs-filserver script has
> to be modified to do ulimit -s unlimited at each startup, as the setting
> is a per-session thing. Speculation as to the cause is welcome.
A per-session setting sounds like a good solution.
> Please don't think a small thing of this. I've spent well over 40
> hours, along with the help of several people to weed this out!
Yes, it sounds like it was quite a lot of work. I'm glad that the
OpenAFS developers were so helpful and responsive, and I hope that
your solution will be found by others in the mailing list archives.
Congrats on recruiting allies and tracking it down!
Ed L Cashin <firstname.lastname@example.org>