Request for review (XS): 7197906: BlockOffsetArray::power_to_cards_back() needs to handle > 32 bit shifts

Bengt Rutisson bengt.rutisson at oracle.com
Thu Sep 13 19:27:55 UTC 2012


Hi Ramki,

Thanks for looking at this!

Here's a webrev based on the second patch that Hal sent out:
http://cr.openjdk.java.net/~brutisso/7197906/webrev.02/

Bengt

On 2012-09-13 18:12, Srinivas Ramakrishna wrote:
> Hal, thanks for the catch and the fix!
>
> Bengt, might it be possible to host this as a traditional webrev in 
> the usual place, to simplify review logistics?
>
> thanks!
> -- ramki
>
> On Thu, Sep 13, 2012 at 4:55 PM, Jianhao Mo <mojianhao at gmail.com 
> <mailto:mojianhao at gmail.com>> wrote:
>
>     Hi all,
>
>     Attached please find the new patch, modified according to John's
>     advice.
>
>     Thanks Bengt again for the help :)
>
>     Regards,
>
>     Hal
>
>     2012/9/12 Jianhao Mo <mojianhao at gmail.com
>     <mailto:mojianhao at gmail.com>>
>
>         Hi all,
>
>         Could I get a couple of reviews for this small patch, please?
>
>         7197906: BlockOffsetArray::power_to_cards_back() needs to
>         handle > 32 bit shifts
>
>         CR link:
>         http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7197906
>         Webrev:
>         http://cr.openjdk.java.net/~brutisso/7197906/webrev.01/
>         <http://cr.openjdk.java.net/%7Ebrutisso/7197906/webrev.01/>
>         Contributed-by:
>         Hal Mo <kungu.mjh at taobao.com <mailto:kungu.mjh at taobao.com>>
>         from Alibaba Group(with OCA)
>
>         It may take a while before the CR link is publicly accessible.
>
>         In blockOffsetTable.hpp, there is an unexpected data
>         truncation in power_to_cards_back(uint i), which may lead to
>         crashing the VM on very large GC heaps.
>         The problem could be reproduced easily on machines, that have
>         enough memory, with:
>         $ java -Xmx135g -XX:+UseConcMarkSweepGC
>
>         The proposed patch fixes this problem, and builds on all
>         OpenJDK supported platforms.
>
>         I'd like to thank Bengt Rutisson for the initial review and
>         help preparing the CR and Webrev.
>
>         Regards,
>         Hal 
>
>
>

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