src/hotspot/os/linux/os_linux.cpp

@@ -127,10 +127,11 @@
 
 // for timer info max values which include all bits
 #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
 
 #define LARGEPAGES_BIT (1 << 6)
+#define DAX_SHARED_BIT (1 << 8)
 ////////////////////////////////////////////////////////////////////////////////
 // global variables
 julong os::Linux::_physical_memory = 0;
 
 address   os::Linux::_initial_thread_stack_bottom = NULL;

@@ -3262,14 +3263,17 @@
 // - (bit 3) file-backed shared memory
 // - (bit 4) ELF header pages in file-backed private memory areas (it is
 //           effective only if the bit 2 is cleared)
 // - (bit 5) hugetlb private memory
 // - (bit 6) hugetlb shared memory
+// - (bit 7) dax private memory
+// - (bit 8) dax shared memory
 //
-static void set_coredump_filter(void) {
+static void set_coredump_filter(bool largepages, bool dax_shared) {
   FILE *f;
   long cdm;
+  bool filter_changed = false;
 
   if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
     return;
   }
 

@@ -3278,12 +3282,19 @@
     return;
   }
 
   rewind(f);
 
-  if ((cdm & LARGEPAGES_BIT) == 0) {
+  if (largepages && (cdm & LARGEPAGES_BIT) == 0) {
     cdm |= LARGEPAGES_BIT;
+    filter_changed = true;
+  }
+  if (dax_shared && (cdm & DAX_SHARED_BIT) == 0) {
+    cdm |= DAX_SHARED_BIT;
+    filter_changed = true;
+  }
+  if (filter_changed) {
     fprintf(f, "%#lx", cdm);
   }
 
   fclose(f);
 }

@@ -3418,11 +3429,11 @@
   }
 
   size_t large_page_size = Linux::setup_large_page_size();
   UseLargePages          = Linux::setup_large_page_type(large_page_size);
 
-  set_coredump_filter();
+  set_coredump_filter(true /*largepages*/, false /*dax_shared*/);
 }
 
 #ifndef SHM_HUGETLB
   #define SHM_HUGETLB 04000
 #endif

@@ -3789,10 +3800,21 @@
 
 bool os::can_execute_large_page_memory() {
   return UseTransparentHugePages || UseHugeTLBFS;
 }
 
+char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr, int file_desc) {
+  assert(file_desc >= 0, "file_desc is not valid");
+  char* result = pd_attempt_reserve_memory_at(bytes, requested_addr);
+  if (result != NULL) {
+    if (replace_existing_mapping_with_file_mapping(result, bytes, file_desc) == NULL) {
+      vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
+    }
+  }
+  return result;
+}
+
 // Reserve memory at an arbitrary address, only if that area is
 // available (and not reserved for something else).
 
 char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
   const int max_tries = 10;

@@ -4916,10 +4938,13 @@
   }
 
   // initialize thread priority policy
   prio_init();
 
+  if (!FLAG_IS_DEFAULT(AllocateHeapAt)) {
+    set_coredump_filter(false /*largepages*/, true /*dax_shared*/); 
+  }
   return JNI_OK;
 }
 
 // Mark the polling page as unreadable
 void os::make_polling_page_unreadable(void) {