ptrace crash on PREEMPT 2.6.18-128.7.1.el5 kernel

[Steve Fink]

On Fri, Feb 26, 2010 at 12:33 PM, Roland McGrath <roland at redhat.com> wrote:
> If you are using actual RHEL5, you can go through your normal support
> channels for help on that.  I don't know off hand of anybody who wants to
> help you with support for using RHEL5 kernel source built with a set of
> options different from what RHEL5's own builds use.  For kernel developers,
> that is a really ancient kernel now.  For enterprise support folks,
> changing big important config options for rebuilding from the stable old
> kernel's source is outside the scope of "stable" and "support".

Fair enough. Thanks for the quick response. For what I'm working on, I
really do need the preemptive kernel (I'm generating a few thousand
different live video streams, so latency=glitches, and preempt
measurably helps.) Which, as you say, pretty much pushes me outside of
the supportable envelope unless we track the bleeding edge, which is
not a good idea for our setup.

But I'm happy to have tracked it down to the utrace-based ptrace
emulation, and was mostly just interested in knowing if preempt and
utrace are fundamentally incompatible on x86_64, or something like
that. I'll fight through the 2.6.18-164 issues instead, since the
ptrace problem doesn't seem to be happening on that version.

Thanks,
Steve