diff --git a/src/ucp/core/ucp_context.h b/src/ucp/core/ucp_context.h
index 371ac68e380..6434f5070b0 100644
--- a/src/ucp/core/ucp_context.h
+++ b/src/ucp/core/ucp_context.h
@@ -25,6 +25,7 @@
 #include <ucs/memory/memory_type.h>
 #include <ucs/memory/rcache.h>
 #include <ucs/type/spinlock.h>
+#include <ucs/sys/checker.h>
 #include <ucs/sys/string.h>
 #include <ucs/type/param.h>
 
@@ -717,6 +718,13 @@ ucp_memory_detect_internal(ucp_context_h context, const void *address,
 
     status = ucs_memtype_cache_lookup(address, length, mem_info);
     if (ucs_likely(status == UCS_ERR_NO_ELEM)) {
+        if (ucs_unlikely(RUNNING_ON_VALGRIND)) {
+            ucs_trace_req("address %p length %zu: not found in memtype cache, "
+                          "detecting memory type under Valgrind", address, length);
+            ucp_memory_detect_slowpath(context, address, length, mem_info);
+            return;
+        }
+
         ucs_trace_req("address %p length %zu: not found in memtype cache, "
                       "assuming host memory",
                       address, length);
diff --git a/src/uct/cuda/base/cuda_iface.c b/src/uct/cuda/base/cuda_iface.c
index 4f788a2a27e..ba3c80d070f 100644
--- a/src/uct/cuda/base/cuda_iface.c
+++ b/src/uct/cuda/base/cuda_iface.c
@@ -211,10 +211,11 @@ uct_cuda_base_ep_flush(uct_ep_h tl_ep, unsigned flags, uct_completion_t *comp)
             goto error;
         }
 
-        flush_stream_desc->flush_desc = flush_desc;
-        flush_stream_desc->comp.func  = uct_cuda_base_stream_flushed_cb;
-        flush_stream_desc->comp.count = 1;
-        flush_stream_desc->super.comp = &flush_stream_desc->comp;
+        flush_stream_desc->flush_desc  = flush_desc;
+        flush_stream_desc->comp.func   = uct_cuda_base_stream_flushed_cb;
+        flush_stream_desc->comp.count  = 1;
+        flush_stream_desc->super.comp  = &flush_stream_desc->comp;
+        flush_stream_desc->super.event = NULL;
         ucs_queue_push(&q_desc->event_queue, &flush_stream_desc->super.queue);
         flush_desc->stream_counter++;
     }
@@ -243,8 +244,7 @@ uct_cuda_base_ep_flush(uct_ep_h tl_ep, unsigned flags, uct_completion_t *comp)
 static UCS_F_ALWAYS_INLINE int
 uct_cuda_base_event_is_flush(const uct_cuda_event_desc_t *event)
 {
-    return (event->comp != NULL) &&
-           (event->comp->func == uct_cuda_base_stream_flushed_cb);
+    return event->event == NULL;
 }
 
 static UCS_F_ALWAYS_INLINE unsigned
diff --git a/src/uct/cuda/cuda_copy/cuda_copy_ep.c b/src/uct/cuda/cuda_copy/cuda_copy_ep.c
index e7545ef7b69..ad968c1bcca 100644
--- a/src/uct/cuda/cuda_copy/cuda_copy_ep.c
+++ b/src/uct/cuda/cuda_copy/cuda_copy_ep.c
@@ -339,6 +339,7 @@ uct_cuda_copy_post_cuda_async_copy(uct_ep_h tl_ep, void *dst, void *src,
         ucs_queue_push(&iface->super.active_queue, &q_desc->queue);
     }
 
+    VALGRIND_MAKE_MEM_DEFINED(&cuda_event->event, sizeof(cuda_event->event));
     ucs_queue_push(event_q, &cuda_event->queue);
     cuda_event->comp = comp;
 
diff --git a/src/uct/cuda/cuda_ipc/cuda_ipc_ep.c b/src/uct/cuda/cuda_ipc/cuda_ipc_ep.c
index e8b62347d1e..16c85969dbc 100644
--- a/src/uct/cuda/cuda_ipc/cuda_ipc_ep.c
+++ b/src/uct/cuda/cuda_ipc/cuda_ipc_ep.c
@@ -19,6 +19,7 @@
 #include <uct/base/uct_log.h>
 #include <uct/base/uct_iov.inl>
 #include <ucs/debug/memtrack_int.h>
+#include <ucs/sys/checker.h>
 #include <ucs/sys/math.h>
 #include <ucs/type/class.h>
 #include <ucs/profile/profile.h>
@@ -177,6 +178,8 @@ uct_cuda_ipc_post_cuda_async_copy(uct_ep_h tl_ep, uint64_t remote_addr,
         ucs_queue_push(&iface->super.active_queue, &q_desc->queue);
     }
 
+    VALGRIND_MAKE_MEM_DEFINED(&cuda_ipc_event->super.event,
+                              sizeof(cuda_ipc_event->super.event));
     ucs_queue_push(&q_desc->event_queue, &cuda_ipc_event->super.queue);
     cuda_ipc_event->super.comp  = comp;
     cuda_ipc_event->mapped_addr = mapped_addr;