RFR: 8369482: JVMTI + Loom: JDK-8368159 introduced safepoint poll in disallowed state [v2]

[Axel Boldt-Christmas]

On Fri, 10 Oct 2025 06:29:40 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

>> [JDK-8368159](https://bugs.openjdk.org/browse/JDK-8368159) added `JvmtiExport::has_frame_pops(JavaThread* thread)`
>> which calls `JvmtiExport::get_jvmti_thread_state();` which may safepoint.
>> 
>> Example stack trace:
>> 
>> V [libjvm.dylib+0x125f888] VMError::report(outputStream*, bool)+0x1b68 (javaThread.cpp:375)
>> V [libjvm.dylib+0x1263184] VMError::report_and_die(int, char const*, char const*, char*, Thread*, unsigned char*, void const*, void const*, char const*, int, unsigned long)+0x55c
>> V [libjvm.dylib+0x5de268] print_error_for_unit_test(char const*, char const*, char*)+0x0
>> V [libjvm.dylib+0x9427ec] JavaThread::check_for_valid_safepoint_state()+0x120
>> V [libjvm.dylib+0xe7e4e4] Mutex::lock(Thread*)+0x48
>> V [libjvm.dylib+0xbbb198] JvmtiThreadState::state_for(JavaThread*, Handle)+0x200
>> V [libjvm.dylib+0xc462ec] JvmtiEventControllerPrivate::thread_started(JavaThread*)+0x1a0
>> V [libjvm.dylib+0xc493a4] JvmtiExport::get_jvmti_thread_state(JavaThread*, bool)+0xc0
>> V [libjvm.dylib+0xc5078c] JvmtiExport::has_frame_pops(JavaThread*)+0x24
>> V [libjvm.dylib+0x59c398] freeze_epilog(JavaThread*, ContinuationWrapper&, freeze_result)+0xf8
>> V [libjvm.dylib+0x59b6e8] Config<(oop_kind)0, CardTableBarrierSet>::freeze(JavaThread*, long*)+0x6f4
>> V [libjvm.dylib+0x59a4d4] int freeze<Config<(oop_kind)0, CardTableBarrierSet>>(JavaThread*, long*)+0x108
>> 
>> 
>> I suggest we do double checked on `JvmtiExport::can_post_frame_pop()` and move the `ContinuationWrapper::SafepointOp` scope.
>
> Axel Boldt-Christmas has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - sspitsyn patch
>  - Revert "8369482: JVMTI + Loom: JDK-8368159 introduced safepoint poll in disallowed state"
>    
>    This reverts commit e133d9b73125ea907111a2a869ed824aca9bfa3d.

Pushed the latest patch. 

The intent of this bug fix was to solve the safepoint (check) issue. 

Is there anything else we should fix as part of this bug fix? Especially given that there is interest in back-porting JDK-8368159.

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PR Comment: https://git.openjdk.org/jdk/pull/27716#issuecomment-3396411952