On Fri, Jun 20, 2014 at 01:43:50PM +0200, Joerg Roedel wrote: > Change_pte is also called when the underlying page of an address > changes in the kernel which would matter for DMA. But that can only > happen in KSM and uprobes code which is probably not of interest for the > i915 driver. > > The other case where I think it matters is the do_wp_page() path for > COW. The code works by calling invalidate_range_start -> change_pte -> > invalidate_range_end. Your driver would react to this by unbinding the > vma from itself internally (after a fork for example). > > But I have to check whether this really matters here. Okay, I think it does not matter for the i915 driver. The code-paths which map pages read-only for COW invoke invalidate_range_start/end on the page-ranges which causes the driver to unbind the pages. When get_user_pages() is called again later it will do the COW by itself, so the driver doesn't need to care. So I tend to say that the i915 driver does not need a change_pte() call-back at all. But probably someone should double-check to make sure I didn't miss something. Joerg _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
