Flickering when creating 2 wl_buffer's for the same dmabuf
When an application creates 2 wl_buffers for the same dmabuf fd via zwp_linux_buffer_params_v1::create()
and attaches it to a subsurface, that subsurface starts flickering.
The flickering does not happen with (nested) Weston.
To reproduce, you can get GTK main and revert gtk@010ff81b and then run build/tests/testdmabuf XR24 ~/some-image.png
and interactive-resize the window.
(You want to either build with Vulkan or sudo chmod 666 /dev/dma_heap/system
or that tool can't create dmabufs)
It will look something like this: