RFR(XS): 8178497: Bug in MutableNUMASpace::ensure_parsability

[Stefan Johansson]

Hi Sangheon,

On 2017-11-20 20:05, sangheon.kim wrote:
> Hi all,
>
> Can I have some reviews for this tiny pointer arithmetic change?
> Current code doesn't use pointer arithmetic, so the the resulting 
> values are wrong(too small). i.e. adding two values first and then 
> typecast to HeapWord* which is wrong here.
> e.g.
> intptr_t cur_top = X;
> size_t touched_words = XX;
> ...
> align_down((HeapWord*)(cur_top + touched_words), XXX);
>
> This should be 'align_down( (HeapWord*)cur_top + touched_words, XXXX);'.
>
> As I don't see any good reason of using 'intptr_t', changed to use 
> 'HeapWord*' and changed related stuff.
>
> I didn't add regression test or some further investigation as this is 
> clear that the calculation is wrong. And hard to provoke the problem 
> outside.
>
> CR: https://bugs.openjdk.java.net/browse/JDK-8178497
> Webrev: http://cr.openjdk.java.net/~sangheki/8178497/webrev.0
Thanks for taking care of this. I think the changes is good, but I would 
feel even more certain if you ran some testing with NUMA and Parallel to 
make sure we haven't overlooked anything.

Thanks,
StefanJ
> Testing: local building
>
> Thanks,
> Sangheon