RFR: 8343191: Cgroup v1 subsystem fails to set subsystem path [v9]

[Sergey Chernyshev]

On Fri, 6 Dec 2024 09:51:52 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Sergey Chernyshev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 13 commits:
>> 
>>  - diverged after integration of JDK-8344177
>>    
>>    # Conflicts:
>>    #	src/java.base/linux/classes/jdk/internal/platform/CgroupUtil.java
>>  - update cgroup v1 in metrics
>>  - Apply suggestions from code review
>>    
>>    Co-authored-by: Severin Gehwolf <jerboaa at gmail.com>
>>  - updated test (path is reduced)
>>  - updated test (path is reduced)
>>  - adjust path suffix in cgroup (v1) version specific code, when root != cgroup
>>  - Merge branch 'master' into JDK-8343191
>>  - warn wenn ../ encountered, update path adjustment
>>  - Update src/hotspot/os/linux/cgroupV1Subsystem_linux.cpp
>>    
>>    Co-authored-by: Severin Gehwolf <jerboaa at gmail.com>
>>  - Merge branch 'master' into JDK-8343191
>>  - ... and 3 more: https://git.openjdk.org/jdk/compare/bd6d911c...2a7e9d82
>
> src/hotspot/os/linux/cgroupV2Subsystem_linux.cpp line 322:
> 
>> 320:     } else {
>> 321:       log_warning(os, container)("Cgroup cpu/memory controller path includes '../', detected limits won't be accurate");
>> 322:     }
> 
> Please move this warning to `CgroupUtil::adjust_controller` and abort the adjustment, we don't need to issue this warning multiple times, and we'd not be able to adjust it to a path that will work. Showing the warning once should be sufficient. We shouldn't see this path in any non-moved scenarios. It would perhaps help if we included some detail why this warning is being shown. I suggest:
> 
> ```cgroup controller path seems to have moved (includes '.../'), detected limits won't be accurate```

Would you recommand also to include the paths in that warning? Something like
```cgroup controller path at '/sys/fs/cgroup' seems to have moved to '../../test', detected limits won't be accurate```
This way it will have all the necessary information to investigate customer cases.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21808#discussion_r1880397873