diff --git a/src/common/host_device_vector.cc b/src/common/host_device_vector.cc
index a3e3ca3c50f0..6ccb1a661739 100644
--- a/src/common/host_device_vector.cc
+++ b/src/common/host_device_vector.cc
@@ -160,7 +160,7 @@ template <typename T>
 void HostDeviceVector<T>::Shard(GPUSet devices) const { }
 
 template <typename T>
-void Reshard(const GPUDistribution &distribution, bool preserve) { }
+void Reshard(const GPUDistribution &distribution) { }
 
 // explicit instantiations are required, as HostDeviceVector isn't header-only
 template class HostDeviceVector<bst_float>;
diff --git a/src/common/host_device_vector.cu b/src/common/host_device_vector.cu
index bb4ff95fdb90..7ed173188dd1 100644
--- a/src/common/host_device_vector.cu
+++ b/src/common/host_device_vector.cu
@@ -370,14 +370,11 @@ struct HostDeviceVectorImpl {
     Shard(GPUDistribution::Block(new_devices));
   }
 
-  void Reshard(const GPUDistribution &distribution, bool preserve) {
+  void Reshard(const GPUDistribution &distribution) {
     if (distribution_ == distribution) { return; }
-    if (preserve) {
-      LazySyncHost(GPUAccess::kWrite);
-    }
+    LazySyncHost(GPUAccess::kWrite);
     distribution_ = distribution;
     shards_.clear();
-    perm_h_.Grant(kWrite);
     InitShards();
   }
 
@@ -604,8 +601,8 @@ void HostDeviceVector<T>::Shard(const GPUDistribution &distribution) const {
 }
 
 template <typename T>
-void HostDeviceVector<T>::Reshard(const GPUDistribution &distribution, bool preserve) {
-  impl_->Reshard(distribution, preserve);
+void HostDeviceVector<T>::Reshard(const GPUDistribution &distribution) {
+  impl_->Reshard(distribution);
 }
 
 template <typename T>
diff --git a/src/common/host_device_vector.h b/src/common/host_device_vector.h
index e019a90ea30f..db27832b623e 100644
--- a/src/common/host_device_vector.h
+++ b/src/common/host_device_vector.h
@@ -259,7 +259,7 @@ class HostDeviceVector {
   /*!
    * \brief Change memory distribution.
    */
-  void Reshard(const GPUDistribution &distribution, bool preserve = true);
+  void Reshard(const GPUDistribution &distribution);
 
   void Resize(size_t new_size, T v = T());
 
diff --git a/tests/cpp/common/test_host_device_vector.cu b/tests/cpp/common/test_host_device_vector.cu
index 1abcdadf0d68..6aca78c81455 100644
--- a/tests/cpp/common/test_host_device_vector.cu
+++ b/tests/cpp/common/test_host_device_vector.cu
@@ -213,7 +213,6 @@ TEST(HostDeviceVector, Reshard) {
   auto span = vec.DeviceSpan(0);  // sync to device
   PlusOne(&vec);
 
-  // GPU data is preserved.
   vec.Reshard(GPUDistribution::Empty());
   ASSERT_EQ(vec.Size(), h_vec.size());
   ASSERT_TRUE(vec.Devices().IsEmpty());
@@ -222,20 +221,6 @@ TEST(HostDeviceVector, Reshard) {
   for (size_t i = 0; i < h_vec_1.size(); ++i) {
     ASSERT_EQ(h_vec_1.at(i), i + 1);
   }
-
-  vec.Reshard(GPUDistribution::Block(devices));
-  span = vec.DeviceSpan(0);  // sync to device
-  PlusOne(&vec);
-
-  vec.Reshard(GPUDistribution::Empty(), /*preserve=*/false);
-  ASSERT_EQ(vec.Size(), h_vec.size());
-  ASSERT_TRUE(vec.Devices().IsEmpty());
-
-  auto h_vec_2 = vec.HostVector();
-  for (size_t i = 0; i < h_vec_2.size(); ++i) {
-    // The second `PlusOne()` has no effect.
-    ASSERT_EQ(h_vec_2.at(i), i + 1);
-  }
 }
 
 TEST(HostDeviceVector, Span) {
@@ -334,27 +319,6 @@ TEST(HostDeviceVector, MGPU_Reshard) {
   for (size_t i = 0; i < h_vec_1.size(); ++i) {
     ASSERT_EQ(h_vec_1.at(i), i + 1);
   }
-
-  for (size_t i = 0; i < devices.Size(); ++i) {
-    auto span = vec.DeviceSpan(i);  // sync to device
-  }
-  PlusOne(&vec);
-
-  vec.Reshard(GPUDistribution::Overlap(devices, 11), /*preserve=*/false);
-  total_size = 0;
-  for (size_t i = 0; i < devices.Size(); ++i) {
-    total_size += vec.DeviceSize(i);
-    devices_size[i] = vec.DeviceSize(i);
-  }
-  overlap = 11 * (devices.Size() - 1);
-  ASSERT_EQ(total_size, h_vec.size() + overlap);
-  ASSERT_EQ(total_size, vec.Size() + overlap);
-
-  auto h_vec_2 = vec.HostVector();
-  for (size_t i = 0; i < h_vec_2.size(); ++i) {
-    // The second `PlusOne()` has no effect.
-    ASSERT_EQ(h_vec_2.at(i), i + 1);
-  }
 }
 #endif