[ Upstream commit 64dcf2f01d59cf9fad19b1a387bd39736a8f4d69 ] [Why] when vram lost happened in guest, try to write vram can lead to kernel stuck. [How] When the readback data is invalid, don't do write work, directly reschedule a new work. Signed-off-by: Jingwen Chen <Jingwen.Chen2@amd.com> Reviewed-by: Monk Liu<monk.liu@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Sasha Levin <sashal@kernel.org>