Quoting Kirill A. Shutemov (2015-03-19 17:08:15) > As far as I can see there's no users of PG_reserved on compound pages. > Let's use NO_COMPOUND here. 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 commit ddf19b973be5a96d77c8467f657fe5bd7d126e0f Author: Dave Airlie <airlied@xxxxxxxx> Date: Sun Mar 19 18:56:12 2006 +1100 drm: fixup PCI DMA support I haven't found anything to say if we are meant to be reserving the pages or not. So I bring it to your attention, asking for help. Thanks, -Chris
