[lworld] Integrated: 8368002: [lworld] Crash in ThawBase::remove_top_compiled_frame_from_chunk

[Patricio Chilano Mateo]

On Fri, 19 Sep 2025 14:40:20 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

This pull request has now been integrated.

Changeset: feee12a2
Author:    Patricio Chilano Mateo <pchilanomate at openjdk.org>
Committer: Coleen Phillimore <coleenp at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/feee12a2ebb8efa5c549ee99510c84f2877ef530
Stats:     47 lines in 1 file changed: 9 ins; 34 del; 4 mod

8368002: [lworld] Crash in ThawBase::remove_top_compiled_frame_from_chunk

Reviewed-by: coleenp

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PR: https://git.openjdk.org/valhalla/pull/1603