fix some bugs introduced by unfreed memory

Author: guochaorong

paddle/fluid/operators/gather_test.cc

@@ -43,7 +43,8 @@ TEST(Gather, GatherData) {
   auto* cpu_place = new paddle::platform::CPUPlace();
   paddle::platform::CPUDeviceContext ctx(*cpu_place);
   paddle::operators::CPUGather<int>(ctx, *src, *index, output);
-
+  delete cpu_place;
+  cpu_place = NULL;
   for (int i = 0; i < 4; ++i) EXPECT_EQ(p_output[i], i + 4);
   for (int i = 4; i < 8; ++i) EXPECT_EQ(p_output[i], i - 4);
 

paddle/fluid/operators/math/math_function_test.cc

@@ -77,6 +77,8 @@ TEST(math_function, gemm_trans_clbas) {
   paddle::platform::CPUDeviceContext context(*cpu_place);
   GetBlas<float>(context).GEMM(false, true, m, n, k, 1, input1_ptr, 3,
                                input2_ptr + 3, 3, 1, input3_ptr + 1, 4);
+  delete cpu_place;
+  cpu_place = NULL;
 
   EXPECT_EQ(input3_ptr[0], 0);
   EXPECT_EQ(input3_ptr[1], 24);

paddle/fluid/platform/device_tracer.cc

@@ -130,6 +130,8 @@ void CUPTIAPI bufferRequested(uint8_t **buffer, size_t *size,
   uint8_t *buf = reinterpret_cast<uint8_t *>(malloc(kBufSize + kAlignSize));
   *size = kBufSize;
   *buffer = ALIGN_BUFFER(buf, kAlignSize);
+  free(buf);
+  buf = NULL;
   *maxNumRecords = 0;
 }