RFR: 8366363: MemBaseline accesses VMT without using lock [v8]

[Johan Sjölen]

On Tue, 2 Sep 2025 11:44:01 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi,
>> 
>> The `MemBaseline` used to access the VMT instance directly without a lock. We fix that, and we switch from using a `LinkedList` to a copied `RegionsTree` instead.
>
> Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Aha, missing include
>  - Wait, the VMATree is wrong?

Sorry about the ridiculous amount of commits. For each one I thought "this is the last one". I've created a temp branch that I'll push to so you don't have to see this WIP.

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PR Comment: https://git.openjdk.org/jdk/pull/27003#issuecomment-3245001621