On Fri, Mar 08, 2019 at 04:58:44PM +0800, Jason Wang wrote: > Can I simply can set_page_dirty() before vunmap() in the mmu notifier > callback, or is there any reason that it must be called within vumap()? I also don't see any problem in doing it before vunmap. As far as the mmu notifier and set_page_dirty is concerned vunmap is just put_page. It's just slower and potentially unnecessary.