8305414: gtest/NMTGtests.java is failing various sub-tests

Reviewed-by: rkennke, adinn

Author: tstuefe

src/hotspot/share/services/mallocTracker.cpp

@@ -194,9 +194,9 @@ void MallocTracker::deaccount(MallocHeader::FreeInfo free_info) {
 
 // Given a pointer, look for the containing malloc block.
 // Print the block. Note that since there is very low risk of memory looking
-// accidentally like a valid malloc block header (canaries and all) this is not
-// totally failproof. Only use this during debugging or when you can afford
-// signals popping up, e.g. when writing an hs_err file.
+// accidentally like a valid malloc block header (canaries and all) so this is not
+// totally failproof and may give a wrong answer. It is safe in that it will never
+// crash, even when encountering unmapped memory.
 bool MallocTracker::print_pointer_information(const void* p, outputStream* st) {
   assert(MemTracker::enabled(), "NMT not enabled");
 
@@ -215,7 +215,7 @@ bool MallocTracker::print_pointer_information(const void* p, outputStream* st) {
     for (; here >= end; here -= smallest_possible_alignment) {
       if (!os::is_readable_pointer(here)) {
         // Probably OOB, give up
-        return false;
+        break;
       }
       const MallocHeader* const candidate = (const MallocHeader*)here;
       if (!candidate->looks_valid()) {

test/hotspot/gtest/nmt/test_nmt_locationprinting.cpp

@@ -47,7 +47,7 @@ static void test_pointer(const void* p, bool expected_return_code, const char* e
 
 static void test_for_live_c_heap_block(size_t sz, ssize_t offset) {
   char* c = NEW_C_HEAP_ARRAY(char, sz, mtTest);
-  LOG_HERE("C-block starts " PTR_FORMAT ", size " SIZE_FORMAT ".", p2i(c), offset);
+  LOG_HERE("C-block starts " PTR_FORMAT ", size " SIZE_FORMAT ".", p2i(c), sz);
   memset(c, 0, sz);
   if (MemTracker::enabled()) {
     const char* expected_string = "into live malloced block";
@@ -69,7 +69,7 @@ static void test_for_dead_c_heap_block(size_t sz, ssize_t offset) {
     return;
   }
   char* c = NEW_C_HEAP_ARRAY(char, sz, mtTest);
-  LOG_HERE("C-block starts " PTR_FORMAT ", size " SIZE_FORMAT ".", p2i(c), offset);
+  LOG_HERE("C-block starts " PTR_FORMAT ", size " SIZE_FORMAT ".", p2i(c), sz);
   memset(c, 0, sz);
   // We cannot just free the allocation to try dead block printing, since the memory
   // may be immediately reused by concurrent code. Instead, we mark the block as dead
@@ -99,13 +99,13 @@ TEST_VM(NMT, location_printing_cheap_live_6) { test_for_live_c_heap_block(4, 0);
 TEST_VM(NMT, location_printing_cheap_live_7) { test_for_live_c_heap_block(4, 4); }                  // just outside a very small block
 
 #ifdef LINUX
-TEST_VM(NMT, DISABLED_location_printing_cheap_dead_1) { test_for_dead_c_heap_block(2 * K, 0); }              // start of payload
-TEST_VM(NMT, DISABLED_location_printing_cheap_dead_2) { test_for_dead_c_heap_block(2 * K, -7); }             // into header
-TEST_VM(NMT, DISABLED_location_printing_cheap_dead_3) { test_for_dead_c_heap_block(2 * K, K + 1); }          // into payload
-TEST_VM(NMT, DISABLED_location_printing_cheap_dead_4) { test_for_dead_c_heap_block(2 * K, K + 2); }          // into payload (check for even/odd errors)
+TEST_VM(NMT, location_printing_cheap_dead_1) { test_for_dead_c_heap_block(2 * K, 0); }              // start of payload
+TEST_VM(NMT, location_printing_cheap_dead_2) { test_for_dead_c_heap_block(2 * K, -7); }             // into header
+TEST_VM(NMT, location_printing_cheap_dead_3) { test_for_dead_c_heap_block(2 * K, K + 1); }          // into payload
+TEST_VM(NMT, location_printing_cheap_dead_4) { test_for_dead_c_heap_block(2 * K, K + 2); }          // into payload (check for even/odd errors)
 TEST_VM(NMT, location_printing_cheap_dead_5) { test_for_dead_c_heap_block(2 * K + 1, 2 * K + 2); }  // just outside payload
-TEST_VM(NMT, DISABLED_location_printing_cheap_dead_6) { test_for_dead_c_heap_block(4, 0); }                  // into a very small block
-TEST_VM(NMT, DISABLED_location_printing_cheap_dead_7) { test_for_dead_c_heap_block(4, 4); }                  // just outside a very small block
+TEST_VM(NMT, location_printing_cheap_dead_6) { test_for_dead_c_heap_block(4, 0); }                  // into a very small block
+TEST_VM(NMT, location_printing_cheap_dead_7) { test_for_dead_c_heap_block(4, 4); }                  // just outside a very small block
 #endif
 
 static void test_for_mmap(size_t sz, ssize_t offset) {