Help: Crash in garbage collection

["Tom Miles" <Tom@...>]

Hi Guys,

I have a problem that I've been tearing my hair out over for the past
day or so.  We have an application that saves out data in a lua
parseable file.  This has been working for a good few months, but we
have found a file that under some as yet unknown condition will crash in
lua when saving.  The crash occurs in sweeplist() at the line:

  while ((curr = *p) != NULL && count-- > 0) {
    if (curr->gch.tt == LUA_TTHREAD)  /* sweep open upvalues of each
thread */

This is called from singlestep, case GCSsweepstring.  I have noticed
that g->sweepstrgc is larger than g->strt.nuse.  Is that a bad thing as
it seems to me like it would be.  If so, how would it get into such a
state?

Any help in tracking this down would be greatly appreciated.  On the
plus side, I now know a little bit more about how lua works internally!
:)

Tom