8268635: Corrupt oop in ClassLoaderData

[coleenp]

We worked on writing a test for this but weren't successful. Based on analysis by @stefank this missing call may have been the cause of the crash.
Tested with tier1-3.

---

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Issue

• JDK-8268635: Corrupt oop in ClassLoaderData

Reviewers

• Ioi Lam (@iklam - Reviewer) ⚠️ Review applies to 1f43b13d27c1903d5e4af5c2d6977a71fd7c24b0
• David Holmes (@dholmes-ora - Reviewer)

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[mlbridge]

Webrevs

• 01: Full (93c33d97)
• 00: Full (1f43b13d)

[iklam]

LGTM

[coleenp]

Thanks Ioi. Sorry about the force push. The github actions were failing because my repo was out of date.

[openjdk]

@coleenp This change now passes all automated pre-integration checks.

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8268635: Corrupt oop in ClassLoaderData Reviewed-by: iklam, dholmes 

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At the time when this comment was updated there had been 2 new commits pushed to the master branch:

• 3d090e7: 8267625: AARCH64: typo in LIR_Assembler::emit_profile_type
• a9e2010: 8268425: Show decimal nid of OSThread instead of hex format one

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[dholmes-ora]

Hi Coleen,

Given the code in add_handle this change seems appropriate. But in looking at the other code I did notice that this call to record_modified_oops in ClassLoaderData::record_dependency seems redundant:

> Handle dependency(Thread::current(), to); > add_handle(dependency); > // Added a potentially young gen oop to the ClassLoaderData > record_modified_oops(); > 

And it did raise a question for me as to whether the code that checks (and potentially clears) _modified_oops can run concurrently with this code, as we set the flag before we actually do the addition in the other methods?

Thanks,
David

[navyxliu]

Hi, Coleen,

Thank you for taking this issue. your code change looks good to me.

IIUC, this PR covers the code path fromModuleEntry::set_shared_protection_domain, where needs record_modified_oops().
ClassLoaderData::record_dependency() seems to have a redundant record_modified_oops, but I don't think it affects correctness.

thanks,
--lx

[coleenp]

Thanks David and Xin, thanks for noticing the clearly redundant record_modified_oops. It was left over from when dependency oops were not in the _handles area.
@dholmes-ora Serial and Parallel GC clear modified oops in a safepoint. I don't remember how G1 used this field. It has some mechanism of claiming the CLD. Maybe @tschatzl or Kim can check it out.

[coleenp]

Thanks @iklam for the review and help trying to write the test.
/integrate

[openjdk]

Going to push as commit 3586a23.
Since your change was applied there have been 8 commits pushed to the master branch:

• bffb1a7: 8269923: runtime/jni/checked/TestPrimitiveArrayCriticalWithBadParam.java failed with "FATAL ERROR in native method: Primitive type array expected but not received for JNI array operation"
• 77a5b7b: 8269761: idea.sh missing .exe suffix when invoking javac on WSL
• 248aa50: 8269294: Verify_before/after_young_collection should execute all verification
• 18b80c7: 8269908: Move MemoryService::track_memory_usage call into G1MonitoringScope
• a685011: 8269022: Put evacuation failure string directly into gc=info log message
• 72530ef: 8269574: C2: Avoid redundant uncommon traps in GraphKit::builtin_throw() for JVMTI exception events
• 3d090e7: 8267625: AARCH64: typo in LIR_Assembler::emit_profile_type
• a9e2010: 8268425: Show decimal nid of OSThread instead of hex format one

Your commit was automatically rebased without conflicts.

[openjdk]

@coleenp Pushed as commit 3586a23.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[earthling-amzn]

/backport jdk15u-dev

[openjdk]

@earthling-amzn Unknown command backport - for a list of valid commands use /help.