RE: Kernel 4.9.x-rt Fully Preemptible Kernel: Issue with gdb and unexpected SIGSTOP signals

From: "Koehrer Mathias (ETAS/ESW5)" <mathias.koehrer@etas.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>
Subject: RE: Kernel 4.9.x-rt Fully Preemptible Kernel: Issue with gdb and unexpected SIGSTOP signals
Date: Wed, 25 Jan 2017 14:00:21 +0000	[thread overview]
Message-ID: <ef2c680e3ed541c4b0df5e0715ca8264@FE-MBX1012.de.bosch.com> (raw)
In-Reply-To: <20170125134016.ffj6xpissz4iy7ph@linutronix.de>

Hi Sebastian,

> > > > > The kernel version 4.1.37-rt43 is working fine, the kernel
> > > > > versions
> > > > > 4.4.39-rt50 and
> > > > 4.8.11-rt7 show the same strange behavior as 4.9.0-rt1.
> > > > > Something on the way between 4.1.37-rt43 and 4.4.39-rt50 seems
> > > > > to cause the
> > > > trouble.
> > > >
> > > > can you check if one of the earlier v4.4-RT releases (maybe start
> > > > with
> > > > -rt2 or -rt1) also shows this behaviour?
> > > > If not, would you have a testcase?
> > > I tested with 4.4.0-rt2.
> > > Here this issue occurs very rarely. I ran the gdb for about 30
> > > times, and here I got one hit.
> > > With the other kernel versions I got the issue in 20-40% of the cases.
> > >
> > > I will try out the other 4.4.0 releases...
> >
> > I ran more tests. The kernel 4.4.1-rt4 is working fairly fine (only
> > about one hit every 30 runs) but the kernel 4.4.1-rt5 is causing the issue very
> often.
> 
> and 4.1.37-rt43 shows not SIGSTOPS in 100 runs?
That's right.
I used 4.1.37-rt43 and ran the test for 200 times. There was no single issue.

Regards

Mathias