On Mon, Feb 03, 2020 at 06:18:44PM +0300, Kirill A. Shutemov wrote: > > Much later than you would ever expect, but we just had a user update an > > ancient device and trip over this. > > https://gitlab.freedesktop.org/drm/intel/issues/1027 > > > > In drm_pci_alloc() we allocate a high-order page (for it to be physically > > contiguous) and mark each page as Reserved. > > > > dmah->vaddr = dma_alloc_coherent(&dev->pdev->dev, size, > > &dmah->busaddr, > > GFP_KERNEL | __GFP_COMP); > > > > /* XXX - Is virt_to_page() legal for consistent mem? */ > > /* Reserve */ > > for (addr = (unsigned long)dmah->vaddr, sz = size; > > sz > 0; addr += PAGE_SIZE, sz -= PAGE_SIZE) { > > SetPageReserved(virt_to_page((void *)addr)); > > } > > > > It's been doing that since This code is completely and utterly broken. Drivers were never allowed to call virt_to_page() on the memory returned from dma_alloc_coherent (or pci_alloc_consistent before that), as many implementations return virtual addresses that are not in the kernel mapping. So this code needs to go away and not papered over.
