From: Christoph Hellwig <hch@xxxxxx> Date: Tue, 18 Dec 2018 19:50:12 +0100 > On Tue, Dec 18, 2018 at 11:43:08AM -0700, Jason Gunthorpe wrote: >> So the problem here is that on some arches >> >> sg_set_buf(sg, dma_coherent_buf, size) >> p = sg_virt(sg); >> assert(p == dma_coherent_buf); > > dma allocations purely return a virtual address, you must never > call virt_to_page or virt_to_phys on them, which sg_set_buf > will do. On many architectures this will give your the wrong > result as the coherent DMA address is a vmap or ioremap address. Correct. And I don't think it makes sense to create fake pages for these remapped areas to resolve to.
