RFR: 8300119: CgroupMetrics.getTotalMemorySize0() can report invalid results on 32 bit systems

[Jonathan Dowland]

This is a fix for https://bugs.openjdk.org/browse/JDK-8300119 (CgroupMetrics.getTotalMemorySize0() can report invalid results on 32 bit systems). Thanks to @jerboaa Severin Gehwolf for figuring out the solution.

The problem is demonstrated by test/hotspot/jtreg/containers/docker/TestMemoryAwareness.java which fails on 32-bit x86 in HEAD, and passes after applying this patch.

I tested this on an amd64 system with a cross-compiled JDK. I needed to override the default docker container for the test, to get one with a 32-bit userland. (the precise choice was also dictated by ABI matching my main development machine):


$JT_HOME/bin/jtreg -v -Djdk.test.docker.retain.image=true -Djdk.test.docker.image.name=i386/debian -Djdk.test.docker.image.version=testing-slim -jdk:$JAVA_HOME test/hotspot/jtreg/containers/docker/TestMemoryAwareness.java

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

Commit messages:
 - 8300119: CgroupMetrics.getTotalMemorySize0() can report invalid results on 32 bit systems

Changes: https://git.openjdk.org/jdk/pull/12069/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12069&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300119
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12069.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12069/head:pull/12069

PR: https://git.openjdk.org/jdk/pull/12069