Re: Undo after cut of a big region says: No further undo information

[Richard Stallman]

    > I put in this feature because Emacs was crashing due to running out of
    > memory due to a very large undo list.  However, I am somewhat unhappy
    > with the consequence that a single operation may be impossible to
    > undo.  I am still not sure what is right to do here.

    How can running out of memory make it crash ?

If malloc fails, Emacs often dies.

    Don't we signal an out of memory error in that case ?

We try to, but it can't always work.  Handling the error needs some
kinds of memory too.  I put in a feature to keep a certain amount of
memory in reserve, for the sake of handling such an error cleanly, but
that doesn't always work either.

I don't remember the details of the case that I was looking at,
but it was probably reported in May.