8374233: Overloaded constructor MountUnmountDisabler(jthread thread) is missed

[sspitsyn]

Please, review a simple fix for a jdk 26 regression: JDK-8364343. It will be pushed to 27 first and then back ported to 26.
This issue impacts JVM TI scalability. The JDK-8364343 replaced the overloaded ctor MountUnmountDisabler(jthread thread) with MountUnmountDisabler(oop thread_oop). This caused the most common JVM TI pattern MountUnmountDisabler disabler(thread) (where thread is a jthread) to be resolved to MountUnmountDisabler(bool exclusive). It makes the instantiated MountUnmountDisabler to disable mount/unmount transitions for all virtual thread instead of the specific one. This problem was identified with a minor tracing.

The fix restores the original ctor MountUnmountDisabler(jthread thread).

Testing:

• TBD: run mach5 tiers 1-6

---

Progress

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Issue

• JDK-8374233: Overloaded constructor MountUnmountDisabler(jthread thread) is missed (Bug - P3)

Reviewers

• Chris Plummer (@plummercj - Reviewer)
• Alex Menkov (@alexmenkov - Reviewer)

Reviewing

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8374233: Overloaded constructor MountUnmountDisabler(jthread thread) is missed

Reviewed-by: cjplummer, amenkov

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At the time when this comment was updated there had been 220 new commits pushed to the master branch:

• 8d80bac: 8374296: Comment clean up in os_linux.cpp
• be2ac08: 8373967: [macos] User interactions with List do not trigger ItemEvent after programmatic change
• f1c5041: 8374200: jdk/internal/platform/cgroup/TestCgroupMetrics.java fails with common prefix metrics
• ... and 217 more: https://git.openjdk.org/jdk/compare/15f25389435288881644f7aeab48fd2eae410999...master

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[sspitsyn]

Chris and Alex, thank you for review!

[sspitsyn]

/integrate

[openjdk]

Going to push as commit f5249db.
Since your change was applied there have been 221 commits pushed to the master branch:

• 61cb6d7: 8374232: Comment cleanup in diagnosticCommand.cpp
• 8d80bac: 8374296: Comment clean up in os_linux.cpp
• be2ac08: 8373967: [macos] User interactions with List do not trigger ItemEvent after programmatic change
• ... and 218 more: https://git.openjdk.org/jdk/compare/15f25389435288881644f7aeab48fd2eae410999...master

Your commit was automatically rebased without conflicts.

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@sspitsyn Pushed as commit f5249db.

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/backport :jdk26

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@sspitsyn the backport was successfully created on the branch backport-sspitsyn-f5249db9-jdk26 in my personal fork of openjdk/jdk. To create a pull request with this backport targeting openjdk/jdk:jdk26, just click the following link:

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Hi all,

This pull request contains a backport of commit f5249db9 from the openjdk/jdk repository.

The commit being backported was authored by Serguei Spitsyn on 23 Dec 2025 and was reviewed by Chris Plummer and Alex Menkov.

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