8358748: Large page size initialization fails with assert "page_size must be a power of 2"

[nelanbu]

The VM now exits gracefully if -XX:LargePageSizeInBytes is set to a non power of two value, instead of asserting. After this change, SizeTTest.java failed because the tested values are not valid for -XX:LargePageSizeInBytes (LargePageSizeInBytesConstraintFunc returns JVMFlag::VIOLATES_CONSTRAINT). Therefore, I updated the test to use NUMASpaceResizeRate, since I believe that it only requires a flag of type size_t.

Before the change:

java -XX:+UseLargePages -XX:LargePageSizeInBytes=6 -version

# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (workspace/open/src/hotspot/share/runtime/os.cpp:2449), pid=1885945, tid=1885946
# assert(is_power_of_2(page_size)) failed: page_size must be a power of 2: 0x6

After the change:

java -XX:+UseLargePages -XX:LargePageSizeInBytes=6 -version

LargePageSizeInBytes ( 6 ) must be a power of 2
Improperly specified VM option 'LargePageSizeInBytes=6'
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

---

Progress

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Issue

• JDK-8358748: Large page size initialization fails with assert "page_size must be a power of 2" (Bug - P4)

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)
• David Holmes (@dholmes-ora - Reviewer)

Reviewing

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[openjdk]

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

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

8358748: Large page size initialization fails with assert "page_size must be a power of 2"

Reviewed-by: ayang, dholmes

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At the time when this comment was updated there had been 16 new commits pushed to the master branch:

• 320235c: 8365700: Jar --validate without any --file option leaves around a temporary file /tmp/tmpJar.jar
• b453eb6: 8365811: test/jdk/java/net/CookieHandler/B6644726.java failure - "Should have 5 cookies. Got only 4, expires probably didn't parse correctly"
• 506625b: 8356324: JVM crash (SIGSEGV at ClassListParser::resolve_indy_impl) during -Xshare:dump starting from 21.0.5
• ... and 13 more: https://git.openjdk.org/jdk/compare/626bea80abf1660757a12462ebc8313ef6d41f92...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.

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Webrevs

• 03: Full - Incremental (6dfa4a29)
• 02: Full (d5fdb70b)
• 01: Full - Incremental (f16b9a57)
• 00: Full (22c33b71)

[dholmes-ora]

The -XX:LargePageSizeInBytes flag seems poorly specified. You can't use an arbitrary value in bytes as a large page size - that is just non-sensical. But I'm not sure this should be a hard error rather than applying "ergonomics" and rounding the supplied value to the nearest power-of-2 (with a warning this has happened).

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@nelanbu This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply issue a /touch or /keepalive command to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[openjdk]

@nelanbu this pull request can not be integrated into master due to one or more merge conflicts. To resolve these merge conflicts and update this pull request you can run the following commands in the local repository for your personal fork:

git checkout JDK-8358748
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push

[albertnetymk]

Therefore, I updated the test to use NUMASpaceResizeRate, since I believe that it only requires a flag of type size_t.

How about LargePageHeapSizeThreshold? It's size_t also. (NUMASpaceResizeRate is a ParallelGC-only flag.)

[nelanbu]

Therefore, I updated the test to use NUMASpaceResizeRate, since I believe that it only requires a flag of type size_t.

How about LargePageHeapSizeThreshold? It's size_t also. (NUMASpaceResizeRate is a ParallelGC-only flag.)

LargePageHeapSizeThreshold would be better. I'll replace it. Thanks for the suggestion @albertnetymk!

[dholmes-ora]

Looks fine. Thnaks

[nelanbu]

Thanks a lot for the reviews! Can I also get a sponsor?

[nelanbu]

/integrate

[openjdk]

@nelanbu
Your change (at version 6dfa4a2) is now ready to be sponsored by a Committer.

[albertnetymk]

/sponsor

[openjdk]

Going to push as commit 40bc083.
Since your change was applied there have been 16 commits pushed to the master branch:

• 320235c: 8365700: Jar --validate without any --file option leaves around a temporary file /tmp/tmpJar.jar
• b453eb6: 8365811: test/jdk/java/net/CookieHandler/B6644726.java failure - "Should have 5 cookies. Got only 4, expires probably didn't parse correctly"
• 506625b: 8356324: JVM crash (SIGSEGV at ClassListParser::resolve_indy_impl) during -Xshare:dump starting from 21.0.5
• ... and 13 more: https://git.openjdk.org/jdk/compare/626bea80abf1660757a12462ebc8313ef6d41f92...master

Your commit was automatically rebased without conflicts.

[openjdk]

@albertnetymk @nelanbu Pushed as commit 40bc083.

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