8292541: [Metrics] Reported memory limit may exceed physical machine memory

Reviewed-by: stuefe, sgehwolf

Author: Jonathan Dowland

src/java.base/linux/classes/jdk/internal/platform/CgroupMetrics.java

@@ -121,7 +121,13 @@ public long getMemoryFailCount() {
 
     @Override
     public long getMemoryLimit() {
-        return subsystem.getMemoryLimit();
+        long subsMem = subsystem.getMemoryLimit();
+        // Catch the cgroup memory limit exceeding host physical memory.
+        // Treat this as unlimited.
+        if (subsMem >= getTotalMemorySize0()) {
+            return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
+        }
+        return subsMem;
     }
 
     @Override
@@ -178,5 +184,6 @@ public static Metrics getInstance() {
     }
 
     private static native boolean isUseContainerSupport();
+    private static native long getTotalMemorySize0();
 
 }

src/java.base/linux/native/libjava/CgroupMetrics.c

@@ -22,6 +22,7 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
+#include <unistd.h>
 
 #include "jni.h"
 #include "jvm.h"
@@ -33,3 +34,10 @@ Java_jdk_internal_platform_CgroupMetrics_isUseContainerSupport(JNIEnv *env, jcla
 {
     return JVM_IsUseContainerSupport();
 }
+
+JNIEXPORT jlong JNICALL
+Java_jdk_internal_platform_CgroupMetrics_getTotalMemorySize0
+  (JNIEnv *env, jclass ignored)
+{
+    return sysconf(_SC_PHYS_PAGES) * sysconf(_SC_PAGESIZE);
+}

test/hotspot/jtreg/containers/docker/TestMemoryAwareness.java

@@ -47,6 +47,13 @@
 public class TestMemoryAwareness {
     private static final String imageName = Common.imageName("memory");
 
+    private static String getHostMaxMemory() throws Exception {
+        DockerRunOptions opts = Common.newOpts(imageName);
+        String goodMem = Common.run(opts).firstMatch("total physical memory: (\\d+)", 1);
+        assertNotNull(goodMem, "no match for 'total physical memory' in trace output");
+        return goodMem;
+    }
+
     public static void main(String[] args) throws Exception {
         if (!DockerTestUtils.canTestDocker()) {
             return;
@@ -79,7 +86,10 @@ public static void main(String[] args) throws Exception {
                 "1G", Integer.toString(((int) Math.pow(2, 20)) * 1024),
                 "1500M", Integer.toString(((int) Math.pow(2, 20)) * (1500 - 1024))
             );
-            testContainerMemExceedsPhysical();
+            final String hostMaxMem = getHostMaxMemory();
+            testOperatingSystemMXBeanIgnoresMemLimitExceedingPhysicalMemory(hostMaxMem);
+            testMetricsIgnoresMemLimitExceedingPhysicalMemory(hostMaxMem);
+            testContainerMemExceedsPhysical(hostMaxMem);
         } finally {
             if (!DockerTestUtils.RETAIN_IMAGE_AFTER_TEST) {
                 DockerTestUtils.removeDockerImage(imageName);
@@ -102,24 +112,16 @@ private static void testMemoryLimit(String valueToSet, String expectedTraceValue
 
     // JDK-8292083
     // Ensure that Java ignores container memory limit values above the host's physical memory.
-    private static void testContainerMemExceedsPhysical()
+    private static void testContainerMemExceedsPhysical(final String hostMaxMem)
             throws Exception {
-
         Common.logNewTestCase("container memory limit exceeds physical memory");
-
-        DockerRunOptions opts = Common.newOpts(imageName);
-
-        // first run: establish physical memory in test environment and derive
-        // a bad value one power of ten larger
-        String goodMem = Common.run(opts).firstMatch("total physical memory: (\\d+)", 1);
-        assertNotNull(goodMem, "no match for 'total physical memory' in trace output");
-        String badMem = goodMem + "0";
-
-        // second run: set a container memory limit to the bad value
-        opts = Common.newOpts(imageName)
+        String badMem = hostMaxMem + "0";
+        // set a container memory limit to the bad value
+        DockerRunOptions opts = Common.newOpts(imageName)
             .addDockerOpts("--memory", badMem);
+
         Common.run(opts)
-            .shouldMatch("container memory limit (ignored: " + badMem + "|unlimited: -1), using host value " + goodMem);
+            .shouldMatch("container memory limit (ignored: " + badMem + "|unlimited: -1), using host value " + hostMaxMem);
     }
 
 
@@ -200,4 +202,23 @@ private static void testOperatingSystemMXBeanAwareness(String memoryAllocation,
         }
     }
 
+
+    // JDK-8292541: Ensure OperatingSystemMXBean ignores container memory limits above the host's physical memory.
+    private static void testOperatingSystemMXBeanIgnoresMemLimitExceedingPhysicalMemory(final String hostMaxMem)
+            throws Exception {
+        String badMem = hostMaxMem + "0";
+        testOperatingSystemMXBeanAwareness(badMem, hostMaxMem, badMem, hostMaxMem);
+    }
+
+    // JDK-8292541: Ensure Metrics ignores container memory limits above the host's physical memory.
+    private static void testMetricsIgnoresMemLimitExceedingPhysicalMemory(final String hostMaxMem)
+            throws Exception {
+        Common.logNewTestCase("Metrics ignore container memory limit exceeding physical memory");
+        String badMem = hostMaxMem + "0";
+        DockerRunOptions opts = Common.newOpts(imageName)
+            .addJavaOpts("-XshowSettings:system")
+            .addDockerOpts("--memory", badMem);
+
+        DockerTestUtils.dockerRunJava(opts).shouldMatch("Memory Limit: Unlimited");
+    }
 }