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Message-ID: <1398661784.30930.33.camel@marge.simpson.net>
Subject: Re: [ANNOUNCE] 3.14-rt1
From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Nicholas Mc Guire <der.herr@hofr.at>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, rostedt@goodmis.org,
        John Kacur <jkacur@redhat.com>
Date: Mon, 28 Apr 2014 07:09:44 +0200
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Hi Nicholas,

On Sat, 2014-04-26 at 15:58 +0200, Mike Galbraith wrote: 
> On Sat, 2014-04-26 at 10:38 +0200, Mike Galbraith wrote: 
> > On Fri, 2014-04-25 at 09:40 +0200, Mike Galbraith wrote:
> > 
> > > Hotplug can still deadlock in rt trees too, and will if you beat it
> > > hard.
> > 
> > Box actually deadlocks like so.
> 
> ...
> 
> 3.12-rt looks a bit busted migrate_disable/enable() wise.
> 
> /me eyeballs 3.10-rt (looks better), confirms 3.10-rt hotplug works,
> swipes working code, confirms 3.12-rt now works.  Yup, that was it.

My boxen, including 64 core DL980 that ran hotplug stress for 3 hours
yesterday with pre-pushdown rwlocks, say the migrate_disable/enable
pushdown patches are very definitely busted.

Instead of whacking selective bits, as I did to verify that the rwlock
changes were indeed causing hotplug stress deadlock woes, I'm eyeballing
the lot, twiddling primitives to look like I think they should, after
which I'll let my boxen express their opinions of the result.

-Mike