RFR: 8069034: gc/g1/TestEagerReclaimHumongousRegionsClearMarkBits.java nightly failure

[Stefan Johansson]

Hi,

Please review this fix for:
https://bugs.openjdk.java.net/browse/JDK-8069034

Webrev:
http://cr.openjdk.java.net/~sjohanss/8069034/hotspot.00/

Summary:
While looking for humongous objects to reclaim we unconditionally 
dirtied cards, some of those might belong to freed regions and if so the 
card table verification will fail. The simple fix is to avoid this by 
checking that the card belong to live regions before dirtying. A more 
robust fix would be to have the iterator avoid returning invalid cards, 
but that is a bigger change and I will file an RFE for this.

Testing:
Manually verified the fix on a host where the problem can be observed.

Thanks,
Stefan