On Tue, Feb 28, 2017 at 10:01:10AM +0100, Daniel Vetter wrote: > > + ret = get_user_pages_unlocked((unsigned long)xfer->mem_addr, > > + vsg->num_pages, vsg->pages, > > + (vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0); Umm... Why not ret = get_user_pages_fast((unsigned long)xfer->mem_addr, vsg->num_pages, vsg->direction == DMA_FROM_DEVICE, vsg->pages); IOW, do you really need a warranty that ->mmap_sem will be grabbed and released? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>