RFR: 8291725: Leftover marks when VM shutdown aborts bitmap clearing make mixed gc fail

[Ivan Walulya]

On Wed, 3 Aug 2022 20:36:44 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   can I have reviews for this change that removes stray bits on the mark bitmap during mixed gcs during shutdown?
> 
> So it may happen that after shutdown aborts the "Concurrent Cleanup for Next Mark" phase which leaves marks on the bitmaps (we want to shut down asap after all). However a mixed gc afterwards might notice these marks and in this case asserts, but in case of an evacuation failure might also trip over these additional marks.
> 
> Testing: tier1-5, I did not manage to reproduce this, but it's "obvious" given the failure mode, particularly because recently there has been a similar issue with full gc in [JDK-8274007](https://bugs.openjdk.org/browse/JDK-8274007)
> 
> Thanks,
>   Thomas

Lgtm!

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Marked as reviewed by iwalulya (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9735