8312620: WSL Linux build crashes after JDK-8310233

Reviewed-by: dholmes, djelinski

src/hotspot/os/linux/hugepages.cpp

@@ -36,7 +36,7 @@
 #include <dirent.h>
 
 StaticHugePageSupport::StaticHugePageSupport() :
-  _initialized(false), _pagesizes(), _default_hugepage_size(SIZE_MAX) {}
+  _initialized(false), _pagesizes(), _default_hugepage_size(SIZE_MAX), _inconsistent(false) {}
 
 os::PageSizes StaticHugePageSupport::pagesizes() const {
   assert(_initialized, "Not initialized");
@@ -141,15 +141,24 @@ void StaticHugePageSupport::print_on(outputStream* os) {
   } else {
     os->print_cr("  unknown.");
   }
+  if (_inconsistent) {
+    os->print_cr("  Support inconsistent. JVM will not use static hugepages.");
+  }
 }
 
 void StaticHugePageSupport::scan_os() {
   _default_hugepage_size = scan_default_hugepagesize();
   if (_default_hugepage_size > 0) {
     _pagesizes = scan_hugepages();
-    assert(_pagesizes.contains(_default_hugepage_size),
-           "Unexpected configuration: default pagesize (" SIZE_FORMAT ") "
-           "has no associated directory in /sys/kernel/mm/hugepages..", _default_hugepage_size);
+    // See https://www.kernel.org/doc/Documentation/vm/hugetlbpage.txt: /proc/meminfo should match
+    // /sys/kernel/mm/hugepages/hugepages-xxxx. However, we may run on a broken kernel (e.g. on WSL)
+    // that only exposes /proc/meminfo but not /sys/kernel/mm/hugepages. In that case, we are not
+    // sure about the state of hugepage support by the kernel, so we won't use static hugepages.
+    if (!_pagesizes.contains(_default_hugepage_size)) {
+      log_info(pagesize)("Unexpected configuration: default pagesize (" SIZE_FORMAT ") "
+                         "has no associated directory in /sys/kernel/mm/hugepages..", _default_hugepage_size);
+      _inconsistent = true;
+    }
   }
   _initialized = true;
   LogTarget(Info, pagesize) lt;

src/hotspot/os/linux/hugepages.hpp

@@ -52,6 +52,9 @@ class StaticHugePageSupport {
   // - is the size one gets when using mmap(MAP_HUGETLB) when omitting size specifiers like MAP_HUGE_SHIFT)
   size_t _default_hugepage_size;
 
+  // If true, the kernel support for hugepages is inconsistent
+  bool _inconsistent;
+
 public:
   StaticHugePageSupport();
 
@@ -60,6 +63,8 @@ public:
   os::PageSizes pagesizes() const;
   size_t default_hugepage_size() const;
   void print_on(outputStream* os);
+
+  bool inconsistent() const { return _inconsistent; }
 };
 
 enum class THPMode { always, never, madvise };
@@ -98,7 +103,7 @@ public:
   static const THPSupport& thp_info() { return _thp_support; }
 
   static size_t default_static_hugepage_size()  { return _static_hugepage_support.default_hugepage_size(); }
-  static bool supports_static_hugepages()       { return default_static_hugepage_size() > 0; }
+  static bool supports_static_hugepages()       { return default_static_hugepage_size() > 0 && !_static_hugepage_support.inconsistent(); }
   static THPMode thp_mode()                     { return _thp_support.mode(); }
   static bool supports_thp()                    { return thp_mode() == THPMode::madvise || thp_mode() == THPMode::always; }
   static size_t thp_pagesize()                  { return _thp_support.pagesize(); }

test/hotspot/jtreg/runtime/os/TestHugePageDetection.java

@@ -29,14 +29,14 @@
  * @requires os.family == "linux"
  * @modules java.base/jdk.internal.misc
  *          java.management
- * @run driver HugePageDetection
+ * @run driver TestHugePageDetection
  */
 
 import java.util.*;
 import jdk.test.lib.process.OutputAnalyzer;
 import jdk.test.lib.process.ProcessTools;
 
-public class HugePageDetection {
+public class TestHugePageDetection {
 
     public static void main(String[] args) throws Exception {