6722565: G1: assert !r->is_on_unclean_list() fires
Summary: Under certain circumstances, two cleanup threads can claim and process the same region.
Reviewed-by: apetrusenko, ysr
a61af66fc99eb5ec9d50c05b0c599757b1289ceb jdk7-b24
7836be3e92d0a4f9ee7566f602c91f5609534e66 jdk7-b25
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c14dab40ed9bf45ad21150bd70c9c80cdf655415 jdk7-b28
4f91c08b3e4498213a9c5a24898f7d9c38cf86fb jdk7-b29