RFR: 8328944: NMT reports "unknown" memory [v2]

[Gerard Ziemski]

On Wed, 20 Nov 2024 10:03:08 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> Gerard Ziemski has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>> 
>>  - avoid using mtNone
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8328944
>>  - revert, we will re-do with a smaller change
>>  - remove more mtNone
>>  - remove API that allows to change the mem_tag for virtual memory, feedback
>>  - do not allow default parameter for mtNone
>
> src/hotspot/share/memory/virtualspace.hpp line 65:
> 
>> 63: 
>> 64:   void initialize(size_t size, size_t alignment, size_t page_size,
>> 65:                   char* requested_address, bool executable, MemTag mem_tag = mtNone);
> 
> When `mtNone` is default, it is still possible to introduce/create regions of Unknown types. The MemTag arg should be mandatory.

Sorry Afshin, I didn't mention it in my summary at the top, but the goal in this fix is only to address the cases covered by the issue. I tried fixing all of them in my 1st try, but Thomas had some reservations. The "missing" cases will be addressed in a follow up(s).

However, I will copy all your feedback, so we don't loose it.

Thank you very much for taking detailed look and providing feedback!

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PR Review Comment: https://git.openjdk.org/jdk/pull/21843#discussion_r1850456338