Support 5 Level Paging and allow mmap to use greater than 128TB of virtual address space on Linux

[Joseph Walker]

Our use case is a dataset exceeding 200TB on a single server with
elasticsearch.  Enabling 5 Level Paging support requires passing a
hint address greater than 47-bit to mmap.
[https://docs.kernel.org/arch/x86/x86_64/5level-paging.html]

The patch below works in our environment and is now used in production:


diff --git a/src/java.base/unix/native/libnio/ch/UnixFileDispatcherImpl.c
b/src/java.base/unix/native/libnio/ch/UnixFileDispatcherImpl.c
index a24f0503e55..23b7068ff21 100644
--- a/src/java.base/unix/native/libnio/ch/UnixFileDispatcherImpl.c
+++ b/src/java.base/unix/native/libnio/ch/UnixFileDispatcherImpl.c
@@ -320,7 +320,7 @@ Java_sun_nio_ch_UnixFileDispatcherImpl_map0(JNIEnv
*env, jclass klass, jobject f
     }

     mapAddress = mmap64(
-        0,                    /* Let OS decide location */
+        (void*)0xFFFFFFFF00000000LL,                    /* Let OS
decide location */
         len,                  /* Number of bytes to map */
         protections,          /* File permissions */
         flags,                /* Changes are shared */


Thanks,
  Joe