RFR (S): 8204169: Humongous continues region remembered set states do not match the one from the corresponding humongous start region

[Thomas Schatzl]

Hi all,

  can I have reviews for this small change that fixes up remembered set
states of humongous continues regions? In particular they are not
necessarily consistent with the humongous starts region at the moment.

This makes for some surprises when reading the logs. Otherwise there is
no impact: all decisions on how to treat the humongous object are made
on the humongous start region anyway.

As for testing, I added code to the heap verification to check this
consistency requirement. This makes for a 100% failure rate in
gc/g1/TestEagerReclaimHumongousRegionsClearMarkBits if not fixed.

CR:
https://bugs.openjdk.java.net/browse/JDK-8204169
Webrev:
http://cr.openjdk.java.net/~tschatzl/8204169/webrev/
Testing:
hs-tier1-3

Thanks,
  Thomas