For a few days after a system update
java/nio/channels/DatagramChannel/SendReceiveMaxSize.java

fails on one of our Linux Ubuntu 22.04 systems.
I tried to make the long message a bit shorter (buffer 100 bytes shorter then the maximum from IPSupport.java) and this still worked.
https://github.com/openjdk/jdk/blob/a2d272a02a079e2413d10ad2decb04681ce2f961/test/lib/jdk/test/lib/net/IPSupport.java#L49

Could it be that on some Linux configs/kernels , the max message size is a bit too long?

test SendReceiveMaxSize.testSendReceiveMaxSize(SendReceiveMaxSize$$Lambda/0x0000000074080c00@20c30ca1, 65527, java.net.Inet6Address@4a3df9e0): failure [3ms]
java.net.SocketException: Message too long
at java.base/sun.nio.ch.DatagramChannelImpl.send0(Native Method)
at java.base/sun.nio.ch.DatagramChannelImpl.sendFromNativeBuffer(DatagramChannelImpl.java:914)
at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:886)
at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:798)
at SendReceiveMaxSize.testSendReceiveMaxSize(SendReceiveMaxSize.java:155)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:599)
at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:174)
at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:822)
at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:147)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1604)
at org.testng.TestRunner.privateRun(TestRunner.java:764)
at org.testng.TestRunner.run(TestRunner.java:585)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:384)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:378)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:337)
at org.testng.SuiteRunner.run(SuiteRunner.java:286)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1218)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1140)
at org.testng.TestNG.runSuites(TestNG.java:1069)
at org.testng.TestNG.run(TestNG.java:1037)
at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:107)
at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:63)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
at java.base/java.lang.Thread.run(Thread.java:1474)
testSendReceiveMaxSize: sender: /[fe80:0:0:0:f816:3eff:fef9:19c7%2]:49794 -> receiver: /[fe80:0:0:0:f816:3eff:fef9:19c7%2]:43898
test SendReceiveMaxSize.testSendReceiveMaxSize(SendReceiveMaxSize$$Lambda/0x0000000074081000@4dd25f07, 65527, java.net.Inet6Address@4a3df9e0): failure [1ms]
java.net.SocketException: Message too long
at java.base/sun.nio.ch.DatagramChannelImpl.send0(Native Method)
at java.base/sun.nio.ch.DatagramChannelImpl.sendFromNativeBuffer(DatagramChannelImpl.java:914)
at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:886)
at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:798)
at SendReceiveMaxSize.testSendReceiveMaxSize(SendReceiveMaxSize.java:155)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:599)
at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:174)
at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:822)
at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:147)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1604)
at org.testng.TestRunner.privateRun(TestRunner.java:764)
at org.testng.TestRunner.run(TestRunner.java:585)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:384)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:378)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:337)
at org.testng.SuiteRunner.run(SuiteRunner.java:286)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1218)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1140)
at org.testng.TestNG.runSuites(TestNG.java:1069)
at org.testng.TestNG.run(TestNG.java:1037)
at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:107)
at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:63)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
at java.base/java.lang.Thread.run(Thread.java:1474)