RFR: 8312132: Add tracking of multiple address spaces in NMT [v46]

[Johan Sjölen]

On Tue, 23 Apr 2024 13:18:18 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Remove faulty condition after removing merging
>>  - Add failing test case
>
> src/hotspot/share/nmt/memTracker.hpp line 184:
> 
>> 182:   }
>> 183: 
>> 184:   static inline void allocate_memory_in(MemoryFileTracker::MemoryFile* device, size_t offset, size_t size,
> 
> invalid args: `nullptr` and `size == 0`.

We should add tests for `size == 0`, but in general I don't think that's a case that we should disallow. This allows for more generic code where the caller doesn't have to special-case the size being 0. Checking for `nullptr` is a good idea in these outer functions.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18289#discussion_r1579224621