On Tue, Sep 15, 2020 at 04:07:19PM +0200, Christoph Hellwig wrote: > 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.
s/zero/NULL/, but the point stands.