hg: jdk/sandbox: 8239785: Cgroups: Incorrect detection logic on old systems in hotspot

[chris.hegarty at oracle.com]

Changeset: d527da8f8f9b
Author:    sgehwolf
Date:      2020-02-25 12:17 +0100
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/d527da8f8f9b

8239785: Cgroups: Incorrect detection logic on old systems in hotspot
Summary: Return NULL subsystem if no cgroup controllers are mounted.
Reviewed-by: bobv, mbaesken

! src/hotspot/os/linux/cgroupSubsystem_linux.cpp
! src/hotspot/os/linux/cgroupSubsystem_linux.hpp
! src/hotspot/share/prims/whitebox.cpp
! src/hotspot/share/prims/whitebox.hpp
+ test/hotspot/jtreg/containers/cgroup/CgroupSubsystemFactory.java
! test/lib/sun/hotspot/WhiteBox.java