RFR: 8351334: [ubsan] memoryReserver.cpp:552:60: runtime error: applying non-zero offset 1073741824 to null pointer [v2]

[Afshin Zafari]

On Thu, 4 Sep 2025 09:34:04 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> The minimum acceptable value was 0 where using it as address was problematic according to UBSAN.
>> The acceptable value is changed to 64K.
>> 
>> Tests:
>> linux-x64 tier1
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   first round of fixes

I preferred to do the refactoring here in this PR.
With the fixes, the assertion `lowest_start < highest_start` raises(fails) in 3 jtreg tests in tier1:

runtime/os/TestTracePageSizes_explicit-large-page-size.java
runtime/CompressedOops/CompressedClassPointers.java
gc/g1/Test2GbHeap.java


In all 3 cases, lowest is the same as the highest start which is a corner case. Are they bugs? Fixed here or file a separate issue?

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PR Comment: https://git.openjdk.org/jdk/pull/26955#issuecomment-3252815844