Re: MPS: profiler

[Eli Zaretskii]

> Date: Fri, 21 Jun 2024 10:49:41 +0000
> From: Pip Cet <pipcet@protonmail.com>
> Cc: Gerd Möllmann <gerd.moellmann@gmail.com>, Eli Zaretskii <eliz@gnu.org>, 
> emacs-devel@gnu.org, eller.helmut@gmail.com
> 
> So, yes, what I described is precisely what we're seeing in the backtrace.

No, you were describing a nested protection-related SIGSEGV.  But we
haven't yet established that the second SIGSEGV is due to protection.
I asked Ihor to show the data in the function that segfaults, but he
didn't do that yet.  Only after we see the data, we can decide that
this is a nested protection-related SIGSEGV, not a segfault caused by
our code accessing data that is no longer there.

In general, I'd expect MPS to be ready for the case where this kind of
combination of signals happens.  At the very least, this is needed for
supporting -gprof, but also for other legitimate techniques.  It is,
of course, possible that MPS has a bug in that area, or even some
design flaw or limitation (in the latter case, it's supposed to be
documented somewhere, btw), but I'd first assume it's our bug, not
theirs, and explore that possibility first.