[jdk8u-dev] RFR: 8291570: [TESTBUG] Part of JDK-8250984 absent from 11u [v2]

[Jonathan Dowland]

> This is a clean backport of 8291570 (from jdk11u) as part of cgroups v2 support.
> 
> The affected test passes for me after the patch.

Jonathan Dowland has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 78 additional commits since the last revision:

 - 8291570: [TESTBUG] Part of JDK-8250984 absent from 11u
   
   Reviewed-by: serb, sgehwolf
 - 8262379: Add regression test for JDK-8257746
   
   Backport-of: 4c9adce20d114a3df629fa8c72d88795039ae69a
 - 8254001: [Metrics] Enhance parsing of cgroup interface files for version detection
   
   Reviewed-by: sgehwolf
   Backport-of: a50725db2ab621e1a17cb5505f78e4bc73972a27
 - 8253797: [cgroups v2] Account for the fact that swap accounting is disabled on some systems
   
   Backport-of: 669361117d30c9904813b6f728714f8d6abe8484
 - 8253939: [TESTBUG] Increase coverage of the cgroups detection code
   
   Backport-of: 42fc15899115ca61151bbee96b5580d4e4252beb
 - replace use of Optional.isEmpty
 - 8245543: Cgroups: Incorrect detection logic on some systems (still reproducible)
   
   Backport-of: 2bbf8a2a964a64d88298a3dd184459af506e58ed
 - Severin's test fixes. Thanks!
 - Replace log_warning with tty->print_cr
 - 8253435: Cgroup: 'stomping of _mount_path' crash if manually mounted cpusets exist
   
   Backport-of: 0054c15f60cce6470be05d29bfacbdb74cfb7bc9
 - ... and 68 more: https://git.openjdk.org/jdk8u-dev/compare/428514ec...a591008b

-------------

Changes:
  - all: https://git.openjdk.org/jdk8u-dev/pull/175/files
  - new: https://git.openjdk.org/jdk8u-dev/pull/175/files/428514ec..a591008b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=175&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=175&range=00-01

  Stats: 4512 lines in 127 files changed: 3220 ins; 781 del; 511 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/175.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/175/head:pull/175

PR: https://git.openjdk.org/jdk8u-dev/pull/175