--- a/gfx/layers/client/CanvasClient.cpp
+++ b/gfx/layers/client/CanvasClient.cpp
@@ -93,18 +93,17 @@ CanvasClient2D::UpdateFromTexture(Textur
 }
 
 void
 CanvasClient2D::Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer)
 {
   mBufferProviderTexture = nullptr;
 
   AutoRemoveTexture autoRemove(this);
-  if (mBackBuffer &&
-      (mBackBuffer->IsImmutable() || mBackBuffer->GetSize() != aSize)) {
+  if (mBackBuffer && (mBackBuffer->IsReadLocked() || mBackBuffer->GetSize() != aSize)) {
     autoRemove.mTexture = mBackBuffer;
     mBackBuffer = nullptr;
   }
 
   bool bufferCreated = false;
   if (!mBackBuffer) {
     bool isOpaque = (aLayer->GetContentFlags() & Layer::CONTENT_OPAQUE);
     gfxContentType contentType = isOpaque
@@ -117,16 +116,17 @@ CanvasClient2D::Update(gfx::IntSize aSiz
       flags |= TextureFlags::ORIGIN_BOTTOM_LEFT;
     }
 
     mBackBuffer = CreateTextureClientForCanvas(surfaceFormat, aSize, flags, aLayer);
     if (!mBackBuffer) {
       NS_WARNING("Failed to allocate the TextureClient");
       return;
     }
+    mBackBuffer->EnableReadLock();
     MOZ_ASSERT(mBackBuffer->CanExposeDrawTarget());
 
     bufferCreated = true;
   }
 
   bool updated = false;
   {
     TextureClientAutoLock autoLock(mBackBuffer, OpenMode::OPEN_WRITE_ONLY);

--- a/gfx/layers/client/ClientCanvasLayer.cpp
+++ b/gfx/layers/client/ClientCanvasLayer.cpp
@@ -85,26 +85,21 @@ void
 ClientCanvasLayer::RenderLayer()
 {
   PROFILER_LABEL("ClientCanvasLayer", "RenderLayer",
     js::ProfileEntry::Category::GRAPHICS);
 
   RenderMaskLayers(this);
 
   if (!mCanvasClient) {
-    TextureFlags flags = TextureFlags::IMMEDIATE_UPLOAD;
+    TextureFlags flags = TextureFlags::DEFAULT;
     if (mOriginPos == gl::OriginPos::BottomLeft) {
       flags |= TextureFlags::ORIGIN_BOTTOM_LEFT;
     }
 
-    if (!mGLContext) {
-      // We don't support locking for buffer surfaces currently
-      flags |= TextureFlags::IMMEDIATE_UPLOAD;
-    }
-
     if (!mIsAlphaPremultiplied) {
       flags |= TextureFlags::NON_PREMULTIPLIED;
     }
 
     mCanvasClient = CanvasClient::CreateCanvasClient(GetCanvasClientType(),
                                                      ClientManager()->AsShadowForwarder(),
                                                      flags);
     if (!mCanvasClient) {