RFR: 8337217: Port VirtualMemoryTracker to use VMATree [v33]

[Gerard Ziemski]

On Tue, 4 Mar 2025 10:08:18 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> test/hotspot/gtest/nmt/test_regions_tree.cpp line 102:
>> 
>>> 100:   rt.commit_region((address)1030, 5UL, ncs);
>>> 101:   rt.commit_region((address)1040, 5UL, ncs);
>>> 102:   ReservedMemoryRegion rmr((address)1000, 50);
>> 
>> I would add something like:
>> 
>>   rt.commit_region((address)1500, 5UL, ncs); // should not be counted
>> 
>> that should not be counted.
>
> adding that line crashes for me as follows:
> 
> Internal Error (<local-path>/src/hotspot/share/nmt/vmatree.cpp:77), pid=87926, tid=87926
> #  assert(leqA_n->val().out.type() != StateType::Released) failed: Should not use inplace the tag of a released region
> #
> 
> It means that we cannot commit without reserving first. The region being committed is released but should be reserved.

I was running it without asserts and didn't see it, but it's good that assert catches it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20425#discussion_r1980126456