Re: iov_iter_pipe warning.

[Al Viro]

On Fri, Apr 28, 2017 at 11:29:55AM -0400, Dave Jones wrote:
> On Fri, Apr 21, 2017 at 06:54:30PM +0100, Al Viro wrote:
>  > On Wed, Apr 12, 2017 at 03:03:18PM -0400, Dave Jones wrote:
>  > 
>  > > Well it's been running an hour without incident, which looks promising.
>  > > I'll leave it run, but I'd say you're on the right track given how quick
>  > > it reproduced so far.
>  > 
>  > Could you try this and see if it works?  What happens is that unlike
>  > e.g. generic_file_read_iter/generic_file_write_iter, NFS O_DIRECT handling
>  > does not make sure that iov_iter had been advanced by the amount
>  > actually transferred - it is left advanced by the amount *requested*.
> 
> Crap. So I never ran it long enough it seems. I can still hit that trace.
> I re-added one of your earlier debug patches, and got this..

Could you send me the diff against something from mainline (identified by
sha1, ideally)?