[lworld] RFR: 8368002: [lworld] Crash in ThawBase::remove_top_compiled_frame_from_chunk [v3]

[Patricio Chilano Mateo]

On Mon, 22 Sep 2025 18:26:55 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Please review this small fix. When thawing in the fast path, the top frame could be a runtime stub due to preempting on monitorenter. In the changes for JDK-8336845 I missed this, leading to a crash when dereferencing the nullptr returned by `f.cb()->as_nmethod_or_null()` in `ThawBase::remove_top_compiled_frame_from_chunk`.
>> 
>> I was able to reproduce the failure locally and verified it is now fixed. I did run into a pre-existing crash with Jetty (filed JDK-8368099). I also run all tests in java/lang/Thread/virtual stressing this path, tests Fuzz.java and TestVirtualThreads.java, plus extra mach5 tier testing.
>> 
>> Thanks,
>> Patricio
>
> Patricio Chilano Mateo has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove chunk parameter from remove_scalarized_frames

Thanks Coleen!

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PR Comment: https://git.openjdk.org/valhalla/pull/1603#issuecomment-3325308382