RFR: 8253435: Cgroup: 'stomping of _mount_path' crash if manually mounted cpusets exist

[Bob Vandette]

> On Sep 23, 2020, at 5:41 AM, Severin Gehwolf <sgehwolf at openjdk.java.net> wrote:
> 
> On Wed, 23 Sep 2020 09:15:38 GMT, Volker Simonis <simonis at openjdk.org> wrote:
> 
>>> _Mailing list message from [Bob Vandette](mailto:bob.vandette at oracle.com) on
>>> [hotspot-runtime-dev](mailto:hotspot-runtime-dev at openjdk.java.net):_ Yuk. I just fixed a bug which caused us to use the
>>> mount source for the cgroup type. Not fixing that bug would have hidden your problem.
>> 
>> Sorry, but I don't understand. which bug are you speaking of and has it been fixed in the jdk already?
> 
> @bobvandette probably meant https://bugs.openjdk.java.net/browse/JDK-8252359. A little correction, though. We didn't
> use the mount source as the cgroup type before JDK-8252359, but we relied on the mount source to be `cgroup` or
> `cgroup2` before JDK-8252359, which wasn't the case on those affected systems. They had the controller name as the
> mount source.

That’s the bug I was referring to.

Bob.

> 
> Bob is right, though, prior JDK-8252359, you wouldn't have hit the assert because of what I just said above. Your extra
> cpuset entries have `none` as mount source.
> 
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> 
> PR: https://git.openjdk.java.net/jdk/pull/295