Re: [LTP] fork07 issues

[Paul L. <pl...@au...>]

On Wed, 2002-02-20 at 07:50, David Engebretsen wrote:
> I think my basic point was missed - it would seem like a good idea to have the
> fork test set the process ulimit to something less than 32K to ensure this
> problem is not hit by others.  As it stands, running fork07 out of the box on
> any 64b platform with sufficient memory will crash the system given the current
> design of the get_pid algorithm in Linux and the default process limits.
> 
> The patch Paul referenced only impacts systems with highmem.  That is not the
> problem in the case of ppc64 as we do not need highmem, so that patch will have
> no effect.  Also, running as root does not really agravate this problem -- any
> user can easily lock up a system while running this fork test, if the system has
> enough memory.  In fact, even if a sys admin sets 'reasonable' user limits, all
> you need are n users running a test like this to lock up the system.
Ahh, ok.  I'm finally starting to wake up this morning. :)

Do you know who is working on fixing this known problem?  I really hate
to change a testcase that is working as designed, and exposing a real
problem with the kernel.  If you don't want to see it happen anymore,
you can comment it out of the runtest/syscalls.

In any case, setting threads-max to a more sane number should work
around this as well, since do_fork() does a check for that before
get_pid is ever called.

-Paul Larson