Re: Crash on invalid cons_free_list

["Richard M. Stallman" <rms@gnu.org>]

    It seems that most of the crashes triggered by VM are somehow related
    to mapcar -- and in this case a mapcar called inside mapatoms.

The crash happens when cons encounters invalid data in the free list.
However, the bug occurred earlier, when the data became invalid.

There is no evidence that it is directly related to this mapcar, or to
this mapatoms.  But if we look at which part of VM does this mapatoms,
then depending on how often it is done, it might offer some sort of
clue.  If VM does this mapatoms very often, perhaps all we can deduce
is that most of VM's consing is there, so if the bug happens in VM, it
would tend to show up there.  That doesn't really help.

However, if only a particular VM command does this mapatoms, and most
of VM's consing is done elsewhere, maybe it means the bug is in
something done by that command.  (Not necessarily WITHIN the
mapatoms--it could be earlier in the same command.)  That could narrow
things down to the point where it would be worth rechecking the C code
for any unusual thing done by that command.