Re: [uml-devel] Integer overflows in new AIO ubd driver

[Gerd Stolpmann <info@gerd-stolpmann.de>]

Am Montag, den 27.03.2006, 10:38 -0500 schrieb Jeff Dike:
> On Sun, Mar 26, 2006 at 08:49:25PM +0200, Gerd Stolpmann wrote:
> > I recently tried to benchmark the new AIO-based ubd driver (including
> > O_DIRECT), and ran into serious problems with filesystems > 4GB. I think
> > I found the problem; two overflows in ubd_kern.c (see patch).
> 
> The first bit looks reasonable.  I would change start to an unsigned
> long long instead of casting, though.
> 
> > I also experienced (hard) lockups when doing lots of I/O. But this seems
> > to be unrelated to this problem (but who knows).
> 
> What was your workload?

I used iozone in various ways. The simplest workload leading to problems
was:

- Write a 5GB file
- Write it again
- Read it back
- Read it back

This benchmark ran fine the first time I started it. When I started it
again, UML locked up in the middle. This is reproducible.

Gerd
-- 
------------------------------------------------------------
Gerd Stolpmann * Viktoriastr. 45 * 64293 Darmstadt * Germany 
gerd@gerd-stolpmann.de          http://www.gerd-stolpmann.de
Phone: +49-6151-153855                  Fax: +49-6151-997714
------------------------------------------------------------



-------------------------------------------------------
This SF.Net email is sponsored by xPML, a groundbreaking scripting language
that extends applications into web and mobile media. Attend the live webcast
and join the prime developer group breaking into this new coding territory!
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel