RFR: 8059066: CardTableModRefBS might commit the same page twice

[Kim Barrett]

On Nov 17, 2014, at 12:43 PM, Erik Helin <erik.helin at oracle.com> wrote:
> 
> Because the start is aligned down and the end is aligned up, the two
> committed regions will always share at least one page (since the start
> for _committed[1] will be aligned down and the end for _committed[0]
> will be aligned up).

I’m just getting back to this today, and haven’t yet refreshed my understanding
of the code.  However, the claim that there will be at least one shared page,
(with followup reasoning for exactly one shared page), doesn’t seem right to me.
It seems to me there could be zero shared pages, since _committed[1] could
(perhaps accidentally, if not by design) be page aligned.