linux-kernel - Re: Strange intermittent EIO error when writing to stdout since v3.8.0

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Date:	Fri, 7 Jun 2013 18:07:04 +0200
From:	Markus Trippelsdorf <markus@...ppelsdorf.de>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Mikael Pettersson <mikpe@...uu.se>,
	David Howells <dhowells@...hat.com>
Subject: Re: Strange intermittent EIO error when writing to stdout since
 v3.8.0

On 2013.06.07 at 11:39 -0400, Peter Hurley wrote:
> On 06/06/2013 10:37 AM, Markus Trippelsdorf wrote:
> > On 2013.06.06 at 10:18 -0400, Peter Hurley wrote:
> >> On 06/06/2013 07:54 AM, Markus Trippelsdorf wrote:
> >>> Since v3.8.0 several people reported intermittent IO errors that happen
> >>> during high system load while using "emerge" under Gentoo:
> >>> ...
> >>>     File "/usr/lib64/portage/pym/portage/util/_eventloop/EventLoop.py", line 260, in iteration
> >>>       if not x.callback(f, event, *x.args):
> >>>     File "/usr/lib64/portage/pym/portage/util/_async/PipeLogger.py", line 99, in _output_handler
> >>>       stdout_buf[os.write(stdout_fd, stdout_buf):]
> >>>     File "/usr/lib64/portage/pym/portage/__init__.py", line 246, in __call__
> >>>       rval = self._func(*wrapped_args, **wrapped_kwargs)
> >>> OSError: [Errno 5] Input/output error
> 
> Based on the other reports from Mikael and David, I suspect this problem
> may have to do with my commit 699390354da6c258b65bf8fa79cfd5feaede50b6:
> 
>    pty: Ignore slave pty close() if never successfully opened
> 
> This commit poisons the pty under certain error conditions that may
> occur from parallel open()s (or parallel close() with pending write()).
> 
> It's unclear to me which error condition is triggered and how user-space
> got an open file descriptor but that seems the most likely. Is the problem
> reproducible enough that a debug patch would likely trigger?

A debug patch would be appreciated.
In my case the problem occurs very irregularly; sometimes it happens a
few times per day, at other times I don't see the bug for three weeks.

But if Mikael and David could also run their kernels with the debug
patch applied, hopefully that's enough to trigger the issue more regularly.

-- 
Markus
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