RFR: 8312132: Add tracking of multiple address spaces in NMT [v5]

[Johan Sjölen]

On Fri, 22 Mar 2024 14:11:55 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Include os.inline.hpp
>
> src/hotspot/share/nmt/vmatree.hpp line 326:
> 
>> 324:       // The releasing API also has no call stack, so we inherit the callstack also.
>> 325:       merge_into.flag = existent.flag;
>> 326:       merge_into.stack_idx = existent.stack_idx;
> 
> Okay, here we don't have to merge at all, no? I don't see any reason to preserve meta info for a released area. 
> 
> Therefore, I would just register the area with mtNone and empty-callstack-id.

There really was a bug associated with not doing this which caused the invariants of in/out nodes to break, there's a test for it :-). It has to do with the `is_noop() && equals` check. Let's see how this changes as I try out following your idea a bit more.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18289#discussion_r1535864052