--- a/src/hotspot/share/gc/epsilon/epsilonHeap.cpp	Tue Oct 16 10:55:28 2018 -0400
+++ b/src/hotspot/share/gc/epsilon/epsilonHeap.cpp	Tue Oct 16 17:43:30 2018 +0200
@@ -47,7 +47,7 @@
   _space->initialize(committed_region, /* clear_space = */ true, /* mangle_space = */ true);
 
   // Precompute hot fields
-  _max_tlab_size = MIN2(CollectedHeap::max_tlab_size(), EpsilonMaxTLABSize / HeapWordSize);
+  _max_tlab_size = MIN2(CollectedHeap::max_tlab_size(), align_object_size(EpsilonMaxTLABSize / HeapWordSize));
   _step_counter_update = MIN2<size_t>(max_byte_size / 16, EpsilonUpdateCountersStep);
   _step_heap_print = (EpsilonPrintHeapSteps == 0) ? SIZE_MAX : (max_byte_size / EpsilonPrintHeapSteps);
   _decay_time_ns = (int64_t) EpsilonTLABDecayTime * NANOSECS_PER_MILLISEC;
@@ -217,6 +217,16 @@
   // Always honor alignment
   size = align_up(size, MinObjAlignment);
 
+  // Check that adjustments did not break local and global invariants
+  assert(is_object_aligned(size),
+         "Size honors object alignment: " SIZE_FORMAT, size);
+  assert(min_size <= size,
+         "Size honors min size: "  SIZE_FORMAT " <= " SIZE_FORMAT, min_size, size);
+  assert(size <= _max_tlab_size,
+         "Size honors max size: "  SIZE_FORMAT " <= " SIZE_FORMAT, size, _max_tlab_size);
+  assert(size <= CollectedHeap::max_tlab_size(),
+         "Size honors global max size: "  SIZE_FORMAT " <= " SIZE_FORMAT, size, CollectedHeap::max_tlab_size());
+
   if (log_is_enabled(Trace, gc)) {
     ResourceMark rm;
     log_trace(gc)("TLAB size for \"%s\" (Requested: " SIZE_FORMAT "K, Min: " SIZE_FORMAT

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/gc/epsilon/TestMaxTLAB.java	Tue Oct 16 17:43:30 2018 +0200
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2018, Red Hat, Inc. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test TestMaxTLAB
+ * @key gc
+ * @requires vm.gc.Epsilon & !vm.graal.enabled
+ * @summary Check EpsilonMaxTLAB options
+ * @bug 8212177
+ *
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=1     TestMaxTLAB
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=1K    TestMaxTLAB
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=1M    TestMaxTLAB
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=12345 TestMaxTLAB
+ *
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=1     -XX:+IgnoreUnrecognizedVMOptions -XX:ObjectAlignmentInBytes=16 TestMaxTLAB
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=1K    -XX:+IgnoreUnrecognizedVMOptions -XX:ObjectAlignmentInBytes=16 TestMaxTLAB
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=1M    -XX:+IgnoreUnrecognizedVMOptions -XX:ObjectAlignmentInBytes=16 TestMaxTLAB
+ * @run main/othervm -XX:+UnlockExperimentalVMOptions -Xmx128m -XX:+UseEpsilonGC -XX:EpsilonMaxTLABSize=12345 -XX:+IgnoreUnrecognizedVMOptions -XX:ObjectAlignmentInBytes=16 TestMaxTLAB
+ */
+
+public class TestMaxTLAB {
+    static Object sink;
+
+    public static void main(String[] args) throws Exception {
+        for (int c = 0; c < 1000; c++) {
+            sink = new byte[c];
+        }
+    }
+}