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Date: Wed, 12 Apr 2017 15:03:18 -0400
From: Dave Jones <davej@codemonkey.org.uk>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: iov_iter_pipe warning.
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On Wed, Apr 12, 2017 at 06:07:23PM +0100, Al Viro wrote:
 > On Wed, Apr 12, 2017 at 12:27:09PM -0400, Dave Jones wrote:
 > 
 > > [ 1010.317696] asked to read 2097152, claims to have read 7025
 > > [ 1010.329471] actual size of data in pipe 65536 
 > > [ 1010.341162] [0:4096
 > > [ 1010.353232] ,1:4096
 > > [ 1010.364402] ,2:4096
 > > [ 1010.375608] ,3:4096
 > > [ 1010.386346] ,4:4096
 > > [ 1010.397027] ,5:4096
 > > [ 1010.407611] ,6:4096
 > > [ 1010.418010] ,7:4096
 > > [ 1010.428533] ,8:4096
 > > [ 1010.438885] ,9:4096
 > > [ 1010.449269] ,10:4096
 > > [ 1010.459462] ,11:4096
 > > [ 1010.469519] ,12:4096
 > > [ 1010.479326] ,13:4096
 > > [ 1010.489093] ,14:4096
 > > [ 1010.498711] ,15:4096
 > > [ 1010.508217] ]
 > > [ 1010.517570] f_op: ffffffffa0242980, f_flags: 311298, pos: 11/7036, size: 7036
 > 
 > 	OK, I see what's going on.  Could you check if the following stops
 > the warnings?  It's not the final variant of fix - there's no need to copy
 > the entire iov_iter, it's just that the primitive needed to deal with that
 > in cleaner way is still not in mainline - davem has pulled it into
 > net.git, but that was after the latest pull from net.git into mainline.
 > 
 > 	For now it should at least tell whether there's something else
 > going on, though:

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.

	Dave