On 1/29/26 15:58, Jason Gunthorpe wrote: > On Thu, Jan 29, 2026 at 07:06:37AM +0000, Tian, Kevin wrote: >> Bear me if it's an ignorant question. >> >> The commit msg of patch6 says that VFIO doesn't tolerate unbounded >> wait, which is the reason behind the 2nd timeout wait here. > > As far as I understand dmabuf design a fence wait should complete > eventually under kernel control, because these sleeps are > sprinkled all around the kernel today.
Well it's a bit different, but we indeed guarantee that dma_fences complete in finite time. > I suspect that is not actually true for every HW, probably something > like "shader programs can run forever technically". Nope, stuff like that is strictly forbidden. Regards, Christian. > > We can argue if those cases should not report revocable either, but at > least this will work "correctly" even if it takes a huge amount of > time. > > I wouldn't mind seeing a shorter timeout and print on the fence too > just in case. > > Jason
