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Re: Getting spurious FAILS in testsuite?


On 08.06.2017 23:33, Andrew Pinski wrote:
On Thu, Jun 8, 2017 at 2:25 PM, Jeff Law <law@redhat.com> wrote:
On 06/08/2017 04:24 AM, Christophe Lyon wrote:
On 8 June 2017 at 11:57, Georg-Johann Lay <avr@gjlay.de> wrote:
On 05.06.2017 18:25, Jim Wilson wrote:

On 06/01/2017 05:59 AM, Georg-Johann Lay wrote:

Hi, when I am running the gcc testsuite in $builddir/gcc then
$ make check-gcc RUNTESTFLAGS='ubsan.exp'
comes up with spurious fails.

This was discussed before, and the suspicion was that it was a linux
kernel bug.  There were multiple kernel fixes pointed at, it wasn't
clear which one was required to fix it.

I have Ubuntu 16.04 LTS on my laptop, and I see the problem.  I can't
run the ubsan testsuites with -j factor greater than one and get
reproducible results.  There may also be other ways to trigger the
problem.

See for instance the thread
     https://gcc.gnu.org/ml/gcc/2016-07/msg00117.html
The first message in the thread from Andrew Pinski mentions that the log
output is corrupted from apparent buffer overflow.

Jim

I have "Ubuntu 16.04.2 LTS".

Asking this at DejaGNU's, I got the following pointer:

https://lists.gnu.org/archive/html/dejagnu/2016-03/msg00034.html

AFAIU there is a problem separating stdout and stderr?


Be careful, I'm not a dejagnu maintainer/developer :-)
I just meant to say I had "similar" problems, but according to this
thread, I'm not the only one :(
There was most definitely a linux kernel bug that affected the behavior
of "expect" used by dejagnu in the past.

THe gcc.gnu.org reference to a message from Pinski is the right one --
it identifies the problematical change in the kernel that mucked up
expect's behavior.

In the thread you'll find a reference to:

https://bugzilla.kernel.org/show_bug.cgi?id=96311

This has long since been fixed.  BUt I have no idea what version of hte
kernel is in Ubuntu and whether or not it is subject to this problem.

I think 4.10 or 4.11 has the full fix.  There was still some bugs even
in 4.8 (which was the one included with Ubuntu 1604).  I only say this
is because I have a 4.8 kernel which sees the problem but a 4.11
kernel does not.  The behavior I see with a non fixed kernel is that
the guailty tests will not run at all.  With the fixed kernel, it will
run.

Thanks,
Andrew

FYI, I am on 4.11.2 now and the spurious FAILs persist.

$ uname -a
Linux 4.11.2-041102-generic #201705201036 SMP ... x86_64 GNU/Linux

$ lsb_release -dicr
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.2 LTS
Release:        16.04
Codename:       xenial

Johann


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