8312492: Remove THP sanity checks at VM startup

Reviewed-by: dholmes, coleenp

Author: tstuefe

src/hotspot/os/linux/os_linux.cpp

@@ -3563,27 +3563,6 @@ bool os::unguard_memory(char* addr, size_t size) {
   return linux_mprotect(addr, size, PROT_READ|PROT_WRITE);
 }
 
-bool os::Linux::transparent_huge_pages_sanity_check(bool warn,
-                                                    size_t page_size) {
-  bool result = false;
-  void *p = mmap(nullptr, page_size * 2, PROT_READ|PROT_WRITE,
-                 MAP_ANONYMOUS|MAP_PRIVATE,
-                 -1, 0);
-  if (p != MAP_FAILED) {
-    void *aligned_p = align_up(p, page_size);
-
-    result = madvise(aligned_p, page_size, MADV_HUGEPAGE) == 0;
-
-    munmap(p, page_size * 2);
-  }
-
-  if (warn && !result) {
-    warning("TransparentHugePages is not supported by the operating system.");
-  }
-
-  return result;
-}
-
 int os::Linux::hugetlbfs_page_size_flag(size_t page_size) {
   if (page_size != HugePages::default_static_hugepage_size()) {
     return (exact_log2(page_size) << MAP_HUGE_SHIFT);
@@ -3715,13 +3694,9 @@ bool os::Linux::setup_large_page_type(size_t page_size) {
   }
 
   if (UseTransparentHugePages) {
-    bool warn_on_failure = !FLAG_IS_DEFAULT(UseTransparentHugePages);
-    if (transparent_huge_pages_sanity_check(warn_on_failure, page_size)) {
-      UseHugeTLBFS = false;
-      UseSHM = false;
-      return true;
-    }
-    UseTransparentHugePages = false;
+    UseHugeTLBFS = false;
+    UseSHM = false;
+    return true;
   }
 
   if (UseHugeTLBFS) {

src/hotspot/os/linux/os_linux.hpp

@@ -76,7 +76,6 @@ class os::Linux {
   static GrowableArray<int>* nindex_to_node()  { return _nindex_to_node; }
 
   static bool setup_large_page_type(size_t page_size);
-  static bool transparent_huge_pages_sanity_check(bool warn, size_t pages_size);
   static bool hugetlbfs_sanity_check(bool warn, size_t page_size);
   static bool shm_hugetlbfs_sanity_check(bool warn, size_t page_size);
 

test/hotspot/jtreg/runtime/memory/LargePages/TestLargePagesFlags.java

@@ -37,6 +37,7 @@
 import jdk.test.lib.process.ProcessTools;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 
 public class TestLargePagesFlags {
 
@@ -299,6 +300,9 @@ public void expect(Flag... expectedFlags) throws Exception {
         throw new IllegalStateException("Must run use() before expect()");
       }
 
+      System.out.println("Using: " + Arrays.toString(useFlags));
+      System.out.println("Expecting: " + Arrays.toString(expectedFlags));
+
       OutputAnalyzer output = executeNewJVM(useFlags);
 
       for (Flag flag : expectedFlags) {
@@ -381,6 +385,9 @@ public String name() {
     public String value() {
       return Boolean.toString(value);
     }
+
+    @Override
+    public String toString() { return flagString(); }
   }
 
   private static interface Flag {