8287073: NPE from CgroupV2Subsystem.getInstance()

[jerboaa]

Backport fixing a potential NPE on cgroups v2.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8287073: NPE from CgroupV2Subsystem.getInstance()

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk11u-dev pull/1339/head:pull/1339
$ git checkout pull/1339

Update a local copy of the PR:
$ git checkout pull/1339
$ git pull https://git.openjdk.org/jdk11u-dev pull/1339/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 1339

View PR using the GUI difftool:
$ git pr show -t 1339

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk11u-dev/pull/1339.diff

[bridgekeeper]

👋 Welcome back sgehwolf! 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]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

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

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

8287073: NPE from CgroupV2Subsystem.getInstance()

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

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[mlbridge]

Webrevs

• 00: Full (c693de0b)

[jerboaa]

/integrate

[openjdk]

Going to push as commit 1afd1f4.
Since your change was applied there have been 4 commits pushed to the master branch:

• 81c2958: 8287107: CgroupSubsystemFactory.setCgroupV2Path asserts with freezer controller
• cbbec73: 8230708: Hotspot fails to build on linux-sparc with gcc-9
• 01db476: 8282947: JFR: Dump on shutdown live-locks in some conditions
• 1d7b292: 8238586: [TESTBUG] vmTestbase/jit/tiered/Test.java failed when TieredCompilation is disabled

Your commit was automatically rebased without conflicts.

[openjdk]

@jerboaa Pushed as commit 1afd1f4.

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