[RFC v14-rc][PATCH 07/23] Restore memory address space

[Serge E. Hallyn]

Quoting Oren Laadan (orenl at cs.columbia.edu):
> +	ret = -EINVAL;
> +	if (hh->vdso != (unsigned long) mm->context.vdso)
> +		goto out;

We were just talking about vdso+s390 on irc this morning,
wondering about how to handle it...

Looking at arch/x86/vdso/vma.c, this seems like it should
pretty much always error out.  The vdso base is set as a
random offset above the stack base at exec().

-serge