RFR: 8059066: CardTableModRefBS might commit the same page twice

[Kim Barrett]

On Nov 24, 2014, at 11:09 AM, Erik Helin <erik.helin at oracle.com> wrote:
> also added an assert to
> how that new_end_aligned <= _committed[ri].end() always is true.

Based on your earlier analysis about there being at most one
overlapping page, I think a tighter assertion could be used, e.g.
something like

new_end_aligned <= (HeapWord*)align_ptr_up(_committed[ri].start() + 1, _page_size)

That would definitely deserve a comment though, and I'm not sure it
adds enough to be worthwhile.

I looked a bit further down in the file, and initially worried about
the uncommit case messing things up, but I think it shouldn't be
possible for a committed region to have zero size because the
associated covered region never has zero size.

> Please
> see new webrevs at:
> - full: http://cr.openjdk.java.net/~ehelin/8059066/webrev.01/index.html
> - inc:  http://cr.openjdk.java.net/~ehelin/8059066/webrev.00-01/index.html

Looks good to me.