8291653: G1 refinement incorrectly expects always-valid HeapRegion out of the Hot Card Cache

[tschatzl]

Hi all,

can I have reviews for this wrong use of G1CollectedHeap::heap_region_containing in G1RemSet::clean_card_before_refine()?

If a card is evicted from the hot card cache it might also be located in an outdated (reclaimed) region (by Remark). So the call needs to explicitly consider that case and use heap_region_containing_or_null and appropriately check for that later.

This is only an issue in debug mode, because while still this is kind of an illegal request, the return value will always be a valid HeapRegion instance as we never deallocate them.

Testing: reproduced crashes with the given test case (1:5), no more crashes afterwards.

Thanks,
Thomas

---

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Issue

• JDK-8291653: G1 refinement incorrectly expects always-valid HeapRegion out of the Hot Card Cache

Reviewers

• Kim Barrett (@kimbarrett - Reviewer)
• Albert Mingkun Yang (@albertnetymk - Reviewer)

Reviewing

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👋 Welcome back tschatzl! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@tschatzl The following label will be automatically applied to this pull request:

• hotspot-gc

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[mlbridge]

Webrevs

• 00: Full (4f0c76d6)

[dcubed-ojdk]

It would be good if this PR got reviewed and integrated soon. The number of
sightings of this test failure is starting to show up on my radar and I'll likely
ProblemList it tomorrow (Fri) if the PR is not integrated soon.

[kimbarrett]

Looks good.

[openjdk]

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8291653: G1 refinement incorrectly expects always-valid HeapRegion out of the Hot Card Cache

Reviewed-by: kbarrett, ayang

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 43 new commits pushed to the master branch:

• 88c96dd: 8291947: riscv: fail to build after JDK-8290840
• dd7f2d9: 8290090: Change CodeBlobType from unscoped enum to enum class
• 4c652d9: 8291952: riscv: Remove PRAGMA_NONNULL_IGNORED
• b0d6952: 8291823: IGV: Fix "Save selected groups"
• 504a626: 8291799: IGV: make "Selection mode" a toggle button
• 6e7cd76: 8291061: Improve thread safety of FileTime.toString and toInstant
• 477f471: Merge
• 4b3dfe1: 8283276: java/io/ObjectStreamClass/ObjectStreamClassCaching.java fails with various GCs
• 6b2184e: 8290248: Implement MaxINode::Ideal transformation
• 27c8826: 8291840: Avoid JavaCalls for setting up _java_system_loader and _java_platform_loader
• ... and 33 more: https://git.openjdk.org/jdk/compare/0971d3464609bf4124df460ea73ff761d7e0f7b2...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[tschatzl]

Thanks @albertnetymk @kimbarrett for your reviews
/integrate

[openjdk]

Going to push as commit f9bb367.
Since your change was applied there have been 45 commits pushed to the master branch:

• b17a745: 8291637: HttpClient default keep alive timeout not followed if server sends invalid value
• 0da4314: 8288732: Reduce runtime of java.util.concurrent microbenchmarks
• 88c96dd: 8291947: riscv: fail to build after JDK-8290840
• dd7f2d9: 8290090: Change CodeBlobType from unscoped enum to enum class
• 4c652d9: 8291952: riscv: Remove PRAGMA_NONNULL_IGNORED
• b0d6952: 8291823: IGV: Fix "Save selected groups"
• 504a626: 8291799: IGV: make "Selection mode" a toggle button
• 6e7cd76: 8291061: Improve thread safety of FileTime.toString and toInstant
• 477f471: Merge
• 4b3dfe1: 8283276: java/io/ObjectStreamClass/ObjectStreamClassCaching.java fails with various GCs
• ... and 35 more: https://git.openjdk.org/jdk/compare/0971d3464609bf4124df460ea73ff761d7e0f7b2...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit f9bb367.

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