On 8/27/22 15:48, Al Viro wrote:

On Sat, Aug 27, 2022 at 01:36:06AM -0700, John Hubbard wrote:

quoted

Convert the NFS Direct IO layer to use pin_user_pages_fast() and
unpin_user_page(), instead of get_user_pages_fast() and put_page().

Again, this stuff can be hit with ITER_BVEC iterators

quoted

-		result = iov_iter_get_pages_alloc2(iter, &pagevec,
+		result = dio_w_iov_iter_pin_pages_alloc(iter, &pagevec,
 						  rsize, &pgbase);

and this will break on those.

If anyone has an example handy, of a user space program that leads
to this situation (O_DIRECT with ITER_BVEC), it would really help
me reach enlightenment a lot quicker in this area. :)

thanks,

-- 
John Hubbard
NVIDIA