Re: Fix to long-standing crashes in GC

[Stefan Monnier]

> I have now found two different cases where a pointer on the stack
> points to GC-managed memory (mem_find finds it), to a cons cell with a
> Lisp_Misc_Free in the car and a bogus list in the cdr.  I suspect there
> are many more such cases.

Right.  And it should never happen.

> I included one such list in my previous mail.

Yes, I've seen it.  Thank you.

>> So I think w need to look further.
> Looking for what?

For what causes Lisp_Misc_Free cells to appear in the car of cons cells that
are apparently live.  I'm not sure how best to do that.  Maybe we should
write a GC-sanity-check routine (scan all cons blocks looking for live cells
with misc free objects in them) that we could call at GC-entry and GC-exit,
this way we could at least see whether the problem happens during GC or
between GC.


        Stefan