diff --git a/src/gfx_apis/vulkan/allocator.rs b/src/gfx_apis/vulkan/allocator.rs
index c7fd5c1a..0cdffd0c 100644
--- a/src/gfx_apis/vulkan/allocator.rs
+++ b/src/gfx_apis/vulkan/allocator.rs
@@ -100,10 +100,12 @@ impl VulkanAllocation {
     }
 
     fn incoherent_range(&self, mask: u64) -> MappedMemoryRange<'static> {
+        let lo = self.offset & !mask;
+        let hi = (self.offset + self.size + mask) & !mask;
         MappedMemoryRange::default()
             .memory(self.memory)
-            .offset(self.offset & !mask)
-            .size((self.size + mask) & !mask)
+            .offset(lo)
+            .size(hi - lo)
     }
 
     fn device(&self) -> &VulkanDevice {
diff --git a/src/gfx_apis/vulkan/renderer.rs b/src/gfx_apis/vulkan/renderer.rs
index 911fa6a8..3d3d1411 100644
--- a/src/gfx_apis/vulkan/renderer.rs
+++ b/src/gfx_apis/vulkan/renderer.rs
@@ -2304,6 +2304,9 @@ where
     }
     let x2 = x2.min(fb.width as i32);
     let y2 = y2.min(fb.height as i32);
+    if x1 == x2 || y1 == y2 {
+        return None;
+    }
     Some([x1, y1, x2, y2])
 }
 
diff --git a/src/gfx_apis/vulkan/shm_image.rs b/src/gfx_apis/vulkan/shm_image.rs
index 06e347d7..0d816fef 100644
--- a/src/gfx_apis/vulkan/shm_image.rs
+++ b/src/gfx_apis/vulkan/shm_image.rs
@@ -258,7 +258,10 @@ impl VulkanShmImage {
                     TransferType::Upload => AccessFlags2::SHADER_SAMPLED_READ,
                     TransferType::Download => AccessFlags2::COLOR_ATTACHMENT_WRITE,
                 })
-                .dst_stage_mask(PipelineStageFlags2::FRAGMENT_SHADER);
+                .dst_stage_mask(match tt {
+                    TransferType::Upload => PipelineStageFlags2::FRAGMENT_SHADER,
+                    TransferType::Download => PipelineStageFlags2::COLOR_ATTACHMENT_OUTPUT,
+                });
         }
         let final_buffer_barrier = memory_barrier(true);
         let final_dep_info = DependencyInfoKHR::default()
diff --git a/src/gfx_apis/vulkan/transfer.rs b/src/gfx_apis/vulkan/transfer.rs
index 13d8bd93..e108bb5a 100644
--- a/src/gfx_apis/vulkan/transfer.rs
+++ b/src/gfx_apis/vulkan/transfer.rs
@@ -54,9 +54,12 @@ pub struct VulkanShmImageAsyncData {
 
 impl VulkanShmImageAsyncData {
     fn complete(&self, result: Result<(), VulkanError>) {
-        self.busy.set(false);
-        if let Some(staging) = self.staging.take() {
-            staging.busy.set(false);
+        let staging = self.staging.take();
+        if result.is_ok() {
+            self.busy.set(false);
+            if let Some(staging) = staging {
+                staging.busy.set(false);
+            }
         }
         self.buffer.take();
         self.client_mem.take();
@@ -676,6 +679,7 @@ fn complete_async_host_copy(
     store(data);
     if let Err(e) = res {
         data.complete(Err(VulkanError::AsyncCopyToStaging(e)));
+        return;
     }
     data.data_copied.set(true);
     match tt {