8358748: Large page size initialization fails with assert "page_size must be a power of 2"

Reviewed-by: ayang, dholmes
Backport-of: 40bc083267c0bac64b1092c63325b8d245937b0e

Author: nelanbu

src/hotspot/share/runtime/flags/jvmFlagConstraintsRuntime.cpp

@@ -147,3 +147,13 @@ JVMFlag::Error NUMAInterleaveGranularityConstraintFunc(size_t value, bool verbos
 
   return JVMFlag::SUCCESS;
 }
+
+JVMFlag::Error LargePageSizeInBytesConstraintFunc(size_t value, bool verbose) {
+  if (!is_power_of_2(value)) {
+    JVMFlag::printError(verbose, "LargePageSizeInBytes ( %zu ) must be "
+                        "a power of 2\n",
+                        value);
+    return JVMFlag::VIOLATES_CONSTRAINT;
+  }
+  return JVMFlag::SUCCESS;
+}

src/hotspot/share/runtime/flags/jvmFlagConstraintsRuntime.hpp

@@ -42,7 +42,8 @@
   f(int,    ContendedPaddingWidthConstraintFunc)      \
   f(int,    PerfDataSamplingIntervalFunc)             \
   f(uintx,  VMPageSizeConstraintFunc)                 \
-  f(size_t, NUMAInterleaveGranularityConstraintFunc)
+  f(size_t, NUMAInterleaveGranularityConstraintFunc)  \
+  f(size_t, LargePageSizeInBytesConstraintFunc)
 
 RUNTIME_CONSTRAINTS(DECLARE_CONSTRAINT)
 

src/hotspot/share/runtime/globals.hpp

@@ -242,8 +242,10 @@ const int ObjectAlignmentInBytes = 8;
                                                                             \
   product(size_t, LargePageSizeInBytes, 0,                                  \
           "Maximum large page size used (0 will use the default large "     \
-          "page size for the environment as the maximum)")                  \
+          "page size for the environment as the maximum) "                  \
+          "(must be a power of 2)")                                         \
           range(0, max_uintx)                                               \
+          constraint(LargePageSizeInBytesConstraintFunc, AtParse)           \
                                                                             \
   product(size_t, LargePageHeapSizeThreshold, 128*M,                        \
           "Use large pages if maximum heap is at least this big")           \

test/lib-test/jdk/test/whitebox/vm_flags/SizeTTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -35,7 +35,7 @@
 import jdk.test.lib.Platform;
 
 public class SizeTTest {
-    private static final String FLAG_NAME = "LargePageSizeInBytes";
+    private static final String FLAG_NAME = "LargePageHeapSizeThreshold";
     private static final Long[] TESTS = {0L, 100L, (long) Integer.MAX_VALUE,
         (1L << 32L) - 1L, 1L << 32L};
     private static final Long[] EXPECTED_64 = TESTS;