RFR: 8287073: NPE from CgroupV2Subsystem.getInstance() [v3]

[Ioi Lam]

On Thu, 26 May 2022 16:04:17 GMT, Maxim Kartashev <mkartashev at openjdk.org> wrote:

>> Following the logic from the comment directly above the changed line, since it doesn't matter which controller we pick, pick any available controller instead of the one called "memory" specifically. This way we are guarded against getting `null` as `anyController`, which is being immediately passed down to `CgroupV2Subsystem.getInstance()` that is unprepared to accept `null` values. 
>> 
>> It is also worth noting that the previous checks (such as that at line 89) make sure that there exist at least one controller in the map.
>
> Maxim Kartashev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Made requested changes

Marked as reviewed by iklam (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/8803