On Sun, Aug 21, 2022 at 09:21:22AM +0100, Alan J. Wylie wrote: > Comparing with another AMD system that doesn't show the problem, > I see that CONFIG_GART_IOMMU is only set on the one with the problem. > > The configs have just had "make oldconfig" run on them for years, I > have no idea why one has it set. > > Clearing it fixes the problem! Thanks for confirming my suspicion. I'd still like to fix the issue with CONFIG_GART_IOMMU enabled once I've tracked it down. Would you be willing to test patches?