[21u] Backport intention of 8322420: [Linux] cgroup v2: Limits in parent nested control groups are not detected

[Jan Kratochvil]

Hello,

I would like to backport:
	https://bugs.openjdk.org/browse/JDK-8322420
	[Linux] cgroup v2: Limits in parent nested control groups are not detected

The whole patchset in a chronological order (the reverse of `git log`):

- <https://github.com/openjdk/jdk/commit/c96cbe481c86800b76e220374b24b6671984adb7>
  <https://bugs.openjdk.org/browse/JDK-8313083> Print 'rss' and 'cache' as part of the container information
  9 files changed, 46 insertions(+), 1 deletion(-)

- <https://github.com/openjdk/jdk/commit/cab74b075e4572529a21bf8ac652ec2f1ab4fcaf>
  <https://bugs.openjdk.org/browse/JDK-8324287> Record total and free swap space in JFR
  patch reduced only to files:
   - src/hotspot/os/linux/os_linux.cpp
   - src/hotspot/share/runtime/os.hpp
  2 files changed, 31 insertions(+)

- <https://github.com/openjdk/jdk/commit/3d106cb091de6b6ef2a9bf483fb0f5c98c28263c>
  <https://bugs.openjdk.org/browse/JDK-8325139> JFR SwapSpace event - add free swap space information on Linux when running in a container environment
  9 files changed, 101 insertions(+), 10 deletions(-)

- <https://github.com/openjdk/jdk/commit/c1281e6b45ed167df69d29a6039d81854c145ae6>
  <https://bugs.openjdk.org/browse/JDK-8324678> Replace NULL with nullptr in HotSpot gtests
  patch reduced only to files:
   - test/hotspot/gtest/runtime/test_os_linux_cgroups.cpp
  1 file changed, 2 insertions(+), 2 deletions(-)

- <https://github.com/openjdk/jdk/commit/09d4936657a0bdc122a4ab80735bd9c8c109839c>
    <https://bugs.openjdk.org/browse/JDK-8252136> Several methods in hotspot are missing "static"
  patch reduced only to files:
   - test/hotspot/gtest/os/linux/test_cgroupSubsystem_linux.cpp
  1 file changed, 5 insertions(+), 5 deletions(-)

- <https://github.com/openjdk/jdk/commit/e889b460c03b3887ec5477fa734c430d3c3a41c8>
  <https://bugs.openjdk.org/browse/JDK-8327071> [Testbug] g-tests for cgroup leave files in /tmp on linux
  1 file changed, 10 insertions(+), 1 deletion(-)

- <https://github.com/openjdk/jdk/commit/3d4eb159e6d597f37081faf21b7e3f0f1af299e5>
  <https://bugs.openjdk.org/browse/JDK-8302744> Refactor Hotspot container detection code
  10 files changed, 862 insertions(+), 590 deletions(-)

- <https://github.com/openjdk/jdk/commit/d0052c032cc1927e7e92f04cfedab20e0c4e0293>
  <https://bugs.openjdk.org/browse/JDK-8333326> Linux Alpine build fails after 8302744
  1 file changed, 9 insertions(+), 5 deletions(-)

- <https://github.com/openjdk/jdk/commit/0a6ffa57954ddf4f92205205a5a1bada813d127a>
  <https://bugs.openjdk.org/browse/JDK-8261242> [Linux] OSContainer::is_containerized() returns true when run outside a container
  18 files changed, 290 insertions(+), 63 deletions(-)

- <https://github.com/openjdk/jdk21u-dev/pull/1330/commits/1ceeb18e6fbf9a7851499b89cba34544ddbcd6dc>
  src/java.base/linux/native/libjava/CgroupMetrics.c:42:(.text+0x11): undefined reference to `JVM_IsContainerized'
  a patch by Yuri Nesterenko, it is not needed in recent JDKs due to <https://bugs.openjdk.org/browse/JDK-8017234>
  1 file changed, 1 insertion(+)

- <https://github.com/openjdk/jdk/commit/153b12b9df87fdf8122cae3bf7f13078f55f7101>
  <https://bugs.openjdk.org/browse/JDK-8331560> Refactor Hotspot container detection code so that subsystem delegates to controllers
  8 files changed, 511 insertions(+), 264 deletions(-)

- <https://github.com/openjdk/jdk/commit/38bd8a36704a962f0ad1052fd2ec150a61663256>
  <https://bugs.openjdk.org/browse/JDK-8338236> Compile error in cgroup code on Linux when using clang
  2 files changed, 5 insertions(+), 5 deletions(-)

- <https://github.com/openjdk/jdk/commit/12d060a255b9b783488714c6c2cb73a899d3f708>
  <https://bugs.openjdk.org/browse/JDK-8339148> Make os::Linux::active_processor_count() public
  unclean but obvious
  1 file changed, 1 insertion(+), 3 deletions(-)

- <https://github.com/openjdk/jdk/commit/55a7cf14453b6cd1de91362927b2fa63cba400a1>
  <https://bugs.openjdk.org/browse/JDK-8322420> [Linux] cgroup v2: Limits in parent nested control groups are not detected
  9 files changed, 362 insertions(+), 111 deletions(-)

- <https://github.com/openjdk/jdk/commit/de55db2352f84c101f8197ee7aca80d72807fbc5>
  <https://bugs.openjdk.org/browse/JDK-8333522> JFR SwapSpace event might read wrong free swap space size
  1 file changed, 4 insertions(+), 1 deletion(-)

Whether they are all needed? They are 3 kinds of pre-requisite patches:
 * non-trivial functionality required by later patches
 * trivial fix-ups which make the later applied patches clean
 * trivial fix-ups of previously applied patch

For easier checking of the backport it was submitted as
https://github.com/openjdk/jdk21u-dev/pull/1330 (a different patch order) but
later I closed it as it should be rather submitted as separate backports.

As the January jdk21u release is imminent I find the April release as the
suitable one.


Thanks,
Jan Kratochvil