8197408: Bad pointer comparison and small cleanup in os_linux.cpp

[jmtd]

This is a backport of JDK-8197408 to jdk8u-dev as part of cgroups v2. I've backported it as a pre-requisite for 8278951: containers/cgroup/PlainRead.java fails on Ubuntu 21.10 (#155)

Most of the original patch has been integrated already: I've left a whitespace change in for os_linux.cpp to hopefully avoid context problems later on. The majority of this patch is introducing the test PlainRead.java.

Not clean: test adjustments to jtreg metadata, imports, and JVM flags needed.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8197408: Bad pointer comparison and small cleanup in os_linux.cpp

Reviewers

• Severin Gehwolf (@jerboaa - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk8u-dev pull/164/head:pull/164
$ git checkout pull/164

Update a local copy of the PR:
$ git checkout pull/164
$ git pull https://git.openjdk.org/jdk8u-dev pull/164/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 164

View PR using the GUI difftool:
$ git pr show -t 164

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk8u-dev/pull/164.diff

[jmtd]

/add 8198833

[bridgekeeper]

👋 Welcome back jdowland! A progress list of the required criteria for merging this PR into pr/136 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]

@jmtd Unknown command add - for a list of valid commands use /help.

[mlbridge]

Webrevs

• 03: Full (f5113461)
• 02: Full - Incremental (0b65ee05)
• 01: Full - Incremental (74d73c96)
• 00: Full (3ef0d0e0)

[jmtd]

Test builds, runs and fails with

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: '^.*CPU Shares is: *(\\d+|-1|Unlimited).*$' missing from stdout/stderr

which I think is resolved by 8278951 (confirming)

Edit: still failing for me in a cgroups v2 host. I think a later backport might resolve it (from memory). TODO I need to re-run the test (both 8197408 and 8278951) on v1.

[jmtd]

The test passes for me in a cgroups v1 host. I think the state (passes on v1, fails on v2) is consistent with the state of things when this patch was committed. I think a later patch might fix this for v2, but it's moot if we consider backporting 8281181, which removes the check against CPU Shares entirely.

[jerboaa]

The test passes for me in a cgroups v1 host. I think the state (passes on v1, fails on v2) is consistent with the state of things when this patch was committed. I think a later patch might fix this for v2

This perhaps? https://bugs.openjdk.org/browse/JDK-8291570

[jmtd]

This perhaps? https://bugs.openjdk.org/browse/JDK-8291570

That's the one! I think we should add this to our cgroups v2 8u list.

[jerboaa]

Looks OK to me. Code changes missing from the patch are already in 8u (and came there with the initial integration 392e56e).

[openjdk-notifier]

@jmtd Please do not rebase or force-push to an active PR as it invalidates existing review comments. All changes will be squashed into a single commit automatically when integrating. See OpenJDK Developers’ Guide for more information.

[bridgekeeper]

@jmtd 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 add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[jerboaa]

Keep open, please.

[openjdk]

@jmtd Please do not rebase or force-push to an active PR as it invalidates existing review comments. All changes will be squashed into a single commit automatically when integrating. See OpenJDK Developers’ Guide for more information.

[openjdk]

@jmtd this pull request can not be integrated into pr/136 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 8197408-jdk8u-dev
git fetch https://git.openjdk.org/jdk8u-dev pr/136
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge pr/136"
git push

[openjdk-notifier]

The parent pull request that this pull request depends on has now been integrated and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork:

git checkout 8197408-jdk8u-dev
git fetch https://git.openjdk.org/jdk8u-dev master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
git commit -m "Merge master"
git push

[openjdk]

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

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

8197408: Bad pointer comparison and small cleanup in os_linux.cpp

Reviewed-by: sgehwolf

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 no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential 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.

[jerboaa]

This cannot be merged as is, needs a rebase.

[openjdk]

@jmtd Please do not rebase or force-push to an active PR as it invalidates existing review comments. All changes will be squashed into a single commit automatically when integrating. See OpenJDK Developers’ Guide for more information.

[jerboaa]

OK. Feel free to integrate and then rebase #155, thanks!

[jmtd]

/integrate

[openjdk]

Going to push as commit c7599bd.

[openjdk]

@jmtd Pushed as commit c7599bd.

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