On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote:
When booting the kernel v5.9-rc4 on a VM, the kernel would panic when
printing a warning message in swiotlb_map(). It is because dev->dma_mask
can potentially be a null pointer. Using the dma_get_mask() macro can
avoid the NULL pointer dereference.
dma_mask must not be zero. This means drm is calling DMA API functions
on something weird. This needs to be fixed in the caller.