diff --git a/ggml/src/ggml-backend.c b/ggml/src/ggml-backend.c
index 5b877db35..96b93d2d8 100644
--- a/ggml/src/ggml-backend.c
+++ b/ggml/src/ggml-backend.c
@@ -1165,6 +1165,11 @@ static int ggml_backend_sched_backend_id_from_cur(ggml_backend_sched_t sched, st
         }
     }
 
+    if (tensor->buffer || (tensor->view_src && tensor->view_src->buffer)) {
+        // since the tensor is pre-allocated, it cannot be moved to another backend
+        GGML_ABORT("pre-allocated tensor in a backend that cannot run the operation");
+    }
+
     // graph input
     if (tensor->flags & GGML_TENSOR_FLAG_INPUT) {
         cur_backend_id = sched->n_backends - 1; // last backend (assumed CPU)
@@ -1644,7 +1649,7 @@ static void ggml_backend_sched_split_graph(ggml_backend_sched_t sched, struct gg
         sched->prev_leaf_backend_ids = tmp;
     }
 
-    int graph_size = graph->n_nodes + sched->n_splits*GGML_SCHED_MAX_SPLIT_INPUTS*2;
+    int graph_size = MAX(graph->n_nodes, graph->n_leafs) + sched->n_splits*GGML_SCHED_MAX_SPLIT_INPUTS*2*sched->n_copies;
     if (sched->graph.size < graph_size) {
         sched->graph.size = graph_size;
         sched->graph.nodes = realloc(sched->graph.nodes, graph_size * sizeof(struct ggml_tensor *));
@@ -1696,6 +1701,7 @@ static void ggml_backend_sched_split_graph(ggml_backend_sched_t sched, struct gg
             for (int c = 0; c < sched->n_copies; c++) {
                 struct ggml_tensor * input_cpy = tensor_id_copy(id, backend_id, c);
                 sched->leaf_backend_ids[graph_copy->n_leafs] = backend_id;
+                assert(graph_copy->size > graph_copy->n_leafs);
                 graph_copy->leafs[graph_copy->n_leafs++] = input_cpy;
             }
         }
@@ -1709,6 +1715,7 @@ static void ggml_backend_sched_split_graph(ggml_backend_sched_t sched, struct gg
                 for (int c = 0; c < sched->n_copies; c++) {
                     struct ggml_tensor * input_cpy = tensor_id_copy(id, backend_id, c);
                     sched->leaf_backend_ids[graph_copy->n_leafs] = backend_id;
+                    assert(graph_copy->size > graph_copy->n_leafs);
                     graph_copy->leafs[graph_copy->n_leafs++] = input_cpy;
                 }
             }
@@ -1719,6 +1726,7 @@ static void ggml_backend_sched_split_graph(ggml_backend_sched_t sched, struct gg
     for (int i = 0; i < graph->n_leafs; i++) {
         struct ggml_tensor * leaf = graph->leafs[i];
         sched->leaf_backend_ids[graph_copy->n_leafs] = tensor_backend_id(leaf);
+        assert(graph_copy->size > graph_copy->n_leafs);
         graph_copy->leafs[graph_copy->n_leafs++] = leaf;
     }
 }
diff --git a/ggml/src/ggml-cuda.cu b/ggml/src/ggml-cuda.cu
index 8a844b02a..d33988d02 100644
--- a/ggml/src/ggml-cuda.cu
+++ b/ggml/src/ggml-cuda.cu
@@ -2572,8 +2572,15 @@ GGML_CALL static enum ggml_status ggml_backend_cuda_graph_compute(ggml_backend_t
                 cuda_ctx->cuda_graph->updated_kernel_arg.push_back((char **) &(node->src[1]->data));
                 // store a pointer to each copy op CUDA kernel to identify it later
                 void * ptr = ggml_cuda_cpy_fn(node->src[0], node->src[1]);
-                if (std::find(ggml_cuda_cpy_fn_ptrs.begin(), ggml_cuda_cpy_fn_ptrs.end(), ptr) == ggml_cuda_cpy_fn_ptrs.end()) {
-                    ggml_cuda_cpy_fn_ptrs.push_back(ptr);
+                if (!ptr) {
+                    use_cuda_graph = false;
+#ifndef NDEBUG
+                    GGML_CUDA_LOG_WARN("%s: disabling CUDA graphs due to unsupported copy op\n", __func__);
+#endif
+                } else {
+                    if (std::find(ggml_cuda_cpy_fn_ptrs.begin(), ggml_cuda_cpy_fn_ptrs.end(), ptr) == ggml_cuda_cpy_fn_ptrs.end()) {
+                        ggml_cuda_cpy_fn_ptrs.push_back(ptr);
+                    }
                 }
             }
 
@@ -2842,6 +2849,9 @@ GGML_CALL static bool ggml_backend_cuda_supports_op(ggml_backend_t backend, cons
                 if (src0_type == GGML_TYPE_F16 && src1_type == GGML_TYPE_F32) {
                     return true;
                 }
+                if (src0_type == src1_type && ggml_is_contiguous(op->src[0]) && ggml_is_contiguous(op->src[1])) {
+                    return true;
+                }
                 return false;
             } break;
         case GGML_OP_DUP:
diff --git a/ggml/src/ggml-cuda/cpy.cu b/ggml/src/ggml-cuda/cpy.cu
index aad34bfe5..51deb75fd 100644
--- a/ggml/src/ggml-cuda/cpy.cu
+++ b/ggml/src/ggml-cuda/cpy.cu
@@ -428,7 +428,10 @@ void ggml_cuda_cpy(ggml_backend_cuda_context & ctx, const ggml_tensor * src0, gg
     char * src0_ddc = (char *) src0->data;
     char * src1_ddc = (char *) src1->data;
 
-    if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_F32) {
+    if (src0->type == src1->type && ggml_is_contiguous(src0) && ggml_is_contiguous(src1)) {
+        GGML_ASSERT(ggml_nbytes(src0) == ggml_nbytes(src1));
+        CUDA_CHECK(cudaMemcpyAsync(src1_ddc, src0_ddc, ggml_nbytes(src0), cudaMemcpyDeviceToDevice, main_stream));
+    } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_F32) {
         ggml_cpy_f32_f32_cuda (src0_ddc, src1_ddc, ne, ne00, ne01, ne02, nb00, nb01, nb02, nb03, ne10, ne11, ne12, nb10, nb11, nb12, nb13, main_stream);
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_F16) {
         ggml_cpy_f32_f16_cuda (src0_ddc, src1_ddc, ne, ne00, ne01, ne02, nb00, nb01, nb02, nb03, ne10, ne11, ne12, nb10, nb11, nb12, nb13, main_stream);
@@ -449,9 +452,8 @@ void ggml_cuda_cpy(ggml_backend_cuda_context & ctx, const ggml_tensor * src0, gg
     } else if (src0->type == GGML_TYPE_F16 && src1->type == GGML_TYPE_F32) {
         ggml_cpy_f16_f32_cuda (src0_ddc, src1_ddc, ne, ne00, ne01, ne02, nb00, nb01, nb02, nb03, ne10, ne11, ne12, nb10, nb11, nb12, nb13, main_stream);
     } else {
-        fprintf(stderr, "%s: unsupported type combination (%s to %s)\n", __func__,
+        GGML_ABORT("%s: unsupported type combination (%s to %s)\n", __func__,
                 ggml_type_name(src0->type), ggml_type_name(src1->type));
-        GGML_ABORT("fatal error");
     }
 }
 
@@ -461,29 +463,30 @@ void ggml_cuda_dup(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
 }
 
 void* ggml_cuda_cpy_fn(const ggml_tensor * src0, ggml_tensor * src1) {
-    if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_F32) {
-            return (void*) cpy_f32_f16<cpy_1_f32_f32>;
+    if (src0->type == src1->type && ggml_is_contiguous(src0) && ggml_is_contiguous(src1)) {
+        return nullptr;
+    } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_F32) {
+        return (void*) cpy_f32_f16<cpy_1_f32_f32>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_F16) {
-            return (void*) cpy_f32_f16<cpy_1_f32_f16>;
+        return (void*) cpy_f32_f16<cpy_1_f32_f16>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_Q8_0) {
-            return (void*) cpy_f32_q<cpy_blck_f32_q8_0, QK8_0>;
+        return (void*) cpy_f32_q<cpy_blck_f32_q8_0, QK8_0>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_Q4_0) {
-            return (void*) cpy_f32_q<cpy_blck_f32_q4_0, QK4_0>;
+        return (void*) cpy_f32_q<cpy_blck_f32_q4_0, QK4_0>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_Q4_1) {
-            return (void*) cpy_f32_q<cpy_blck_f32_q4_1, QK4_1>;
+        return (void*) cpy_f32_q<cpy_blck_f32_q4_1, QK4_1>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_Q5_0) {
-            return (void*) cpy_f32_q<cpy_blck_f32_q5_0, QK5_0>;
+        return (void*) cpy_f32_q<cpy_blck_f32_q5_0, QK5_0>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_IQ4_NL) {
-            return (void*) cpy_f32_q<cpy_blck_f32_iq4_nl, QK4_NL>;
+        return (void*) cpy_f32_q<cpy_blck_f32_iq4_nl, QK4_NL>;
     } else if (src0->type == GGML_TYPE_F32 && src1->type == GGML_TYPE_Q5_1) {
-            return (void*) cpy_f32_q<cpy_blck_f32_q5_1, QK5_1>;
+        return (void*) cpy_f32_q<cpy_blck_f32_q5_1, QK5_1>;
     } else if (src0->type == GGML_TYPE_F16 && src1->type == GGML_TYPE_F16) {
-            return (void*) cpy_f32_f16<cpy_1_f32_f16>;
+        return (void*) cpy_f32_f16<cpy_1_f32_f16>;
     } else if (src0->type == GGML_TYPE_F16 && src1->type == GGML_TYPE_F32) {
-            return (void*) cpy_f32_f16<cpy_1_f16_f32>;
+        return (void*) cpy_f32_f16<cpy_1_f16_f32>;
     } else {
-        fprintf(stderr, "%s: unsupported type combination (%s to %s)\n", __func__,
+        GGML_ABORT("%s: unsupported type combination (%s to %s)\n", __func__,
                 ggml_type_name(src0->type), ggml_type_name(src1->type));
-        GGML_ABORT("fatal error");
     }
 }