8253714: [cgroups v2] Soft memory limit incorrectly using memory.high

The early implementation of cgroups v2 support was done with
crun 0.8 and it contained a bug which set memory.high over
memory.low when --memory-reservation was being used as a CLI
option.

This bug has been fixed in later crun versions, starting with
crun 0.11. Use memory.low in OpenJDK as well.

Reviewed-by: andrew
Backport-of: ff6843ca4842498791061f924c545fa9469cc1dc

Author: Jonathan Dowland

hotspot/src/os/linux/vm/cgroupV2Subsystem_linux.cpp

@@ -161,7 +161,7 @@ jlong CgroupV2Subsystem::memory_max_usage_in_bytes() {
 }
 
 char* CgroupV2Subsystem::mem_soft_limit_val() {
-  GET_CONTAINER_INFO_CPTR(cptr, _unified, "/memory.high",
+  GET_CONTAINER_INFO_CPTR(cptr, _unified, "/memory.low",
                          "Memory Soft Limit is: %s", "%s", mem_soft_limit_str, 1024);
   if (mem_soft_limit_str == NULL) {
     return NULL;

jdk/src/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2Subsystem.java

@@ -292,7 +292,7 @@ public long getMemoryAndSwapUsage() {
 
     @Override
     public long getMemorySoftLimit() {
-        String softLimitStr = CgroupSubsystemController.getStringValue(unified, "memory.high");
+        String softLimitStr = CgroupSubsystemController.getStringValue(unified, "memory.low");
         return limitFromString(softLimitStr);
     }
 

jdk/test/lib/jdk/test/lib/containers/cgroup/MetricsTesterCgroupV2.java

@@ -245,9 +245,9 @@ public void testMemorySubsystem() {
         }
 
         oldVal = metrics.getMemorySoftLimit();
-        newVal = getLongLimitValueFromFile("memory.high");
+        newVal = getLongLimitValueFromFile("memory.low");
         if (!CgroupMetricsTester.compareWithErrorMargin(oldVal, newVal)) {
-            fail("memory.high", oldVal, newVal);
+            fail("memory.low", oldVal, newVal);
         }
 
     }