From 755d8ad8863d569f68e9772882e216ec592cff89 Mon Sep 17 00:00:00 2001
From: Tarang Jain <jaintarang2015@gmail.com>
Date: Mon, 30 Mar 2026 12:50:53 -0700
Subject: [PATCH 1/2] fix vamana serialization bug

---
 .../detail/vamana/vamana_serialize.cuh        | 22 +++++++++++++------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh b/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh
index 887c9eb448..e39a9e7ae4 100644
--- a/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh
+++ b/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh
@@ -65,13 +65,20 @@ void serialize_dataset(raft::resources const& res,
     const auto* strided_dataset =
       dynamic_cast<const cuvs::neighbors::strided_dataset<T, int64_t>*>(dataset);
     if (strided_dataset) {
-      auto h_dataset =
-        raft::make_host_matrix<T, int64_t>(strided_dataset->n_rows(), strided_dataset->dim());
-      raft::copy(res,
-                 raft::make_host_vector_view(h_dataset.data_handle(),
-                                             strided_dataset->n_rows() * strided_dataset->dim()),
-                 raft::make_device_vector_view(strided_dataset->view().data_handle(),
-                                               strided_dataset->n_rows() * strided_dataset->dim()));
+      auto nrows     = strided_dataset->n_rows();
+      auto dim       = strided_dataset->dim();
+      auto stride    = strided_dataset->stride();
+      auto d_data    = strided_dataset->view();
+      auto h_dataset = raft::make_host_matrix<T, int64_t>(nrows, dim);
+      RAFT_CUDA_TRY(cudaMemcpy2DAsync(h_dataset.data_handle(),
+                                      sizeof(T) * dim,
+                                      d_data.data_handle(),
+                                      sizeof(T) * stride,
+                                      sizeof(T) * dim,
+                                      nrows,
+                                      cudaMemcpyDefault,
+                                      raft::resource::get_cuda_stream(res)));
+      raft::resource::sync_stream(res);
       to_file(dataset_base_file, h_dataset);
     } else {
       RAFT_LOG_DEBUG("dynamic_cast to strided_dataset failed");
@@ -91,6 +98,7 @@ void serialize_dataset(raft::resources const& res,
   try {
     auto h_dataset = raft::make_host_matrix<T, int64_t>(dataset.extent(0), dataset.extent(1));
     raft::copy(res, h_dataset.view(), dataset);
+    raft::resource::sync_stream(res);
     to_file(dataset_base_file, h_dataset);
   } catch (std::bad_alloc& e) {
     RAFT_LOG_INFO("Failed to serialize dataset");

From 3806ab36715fac194104d828bb6ab85393caf9a1 Mon Sep 17 00:00:00 2001
From: Tarang Jain <jaintarang2015@gmail.com>
Date: Tue, 31 Mar 2026 20:06:52 -0700
Subject: [PATCH 2/2] raft::copy_matrix

---
 .../neighbors/detail/vamana/vamana_serialize.cuh | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh b/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh
index e39a9e7ae4..68ce334cd2 100644
--- a/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh
+++ b/cpp/src/neighbors/detail/vamana/vamana_serialize.cuh
@@ -16,6 +16,7 @@
 #include <raft/core/nvtx.hpp>
 #include <raft/core/resource/cuda_stream.hpp>
 #include <raft/core/serialize.hpp>
+#include <raft/util/cudart_utils.hpp>
 
 #include "../dataset_serialize.hpp"
 
@@ -70,14 +71,13 @@ void serialize_dataset(raft::resources const& res,
       auto stride    = strided_dataset->stride();
       auto d_data    = strided_dataset->view();
       auto h_dataset = raft::make_host_matrix<T, int64_t>(nrows, dim);
-      RAFT_CUDA_TRY(cudaMemcpy2DAsync(h_dataset.data_handle(),
-                                      sizeof(T) * dim,
-                                      d_data.data_handle(),
-                                      sizeof(T) * stride,
-                                      sizeof(T) * dim,
-                                      nrows,
-                                      cudaMemcpyDefault,
-                                      raft::resource::get_cuda_stream(res)));
+      raft::copy_matrix(h_dataset.data_handle(),
+                        dim,
+                        d_data.data_handle(),
+                        stride,
+                        dim,
+                        nrows,
+                        raft::resource::get_cuda_stream(res));
       raft::resource::sync_stream(res);
       to_file(dataset_base_file, h_dataset);
     } else {