linux-kernel - Re: [PATCH RT 4/8] rtmutex: use a trylock for waiter lock in trylock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140131220737.GF21238@linutronix.de>
Date:	Fri, 31 Jan 2014 23:07:37 +0100
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	Mike Galbraith <bitbucket@...ine.de>
Cc:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	linux-rt-users <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Carsten Emde <C.Emde@...dl.org>, John Kacur <jkacur@...hat.com>
Subject: Re: [PATCH RT 4/8] rtmutex: use a trylock for waiter lock in trylock

* Mike Galbraith | 2014-01-17 06:17:12 [+0100]:

>On Thu, 2014-01-16 at 23:22 -0500, Steven Rostedt wrote: 
>> On Thu, 16 Jan 2014 04:08:57 +0100
>> Mike Galbraith <bitbucket@...ine.de> wrote:
>> 
>> > On Wed, 2014-01-15 at 20:58 -0500, Steven Rostedt wrote:
>> > 
>> > 
>> > > 3.2.53-rt76-rc1 stable review patch.
>> > > If anyone has any objections, please let me know.
>> > 
>> > Not sure this is needed without the tglx don't unconditionally raise
>> > timer softirq patch, and with that patch applied in the form it exists
>> > in 3.12-rt9, as well as this one, you'll still eventually deadlock.
>> 
>> Hmm, I'll have to take a look. This sounds to be missing from all the
>> stable -rt kernels. I'll be pulling in the latest updates from 3.12-rt
>> soon.
>
>Below are the two deadlocks I encountered with 3.12-rt9, which has both
>$subject and timers-do-not-raise-softirq-unconditionally.patch applied.

This patch was introduced because we had a deadlock in
run_local_timers() which took a sleeping lock in hardirq context. This
seem not to be the case in v3.2 therefore I would suggest not to take
this patch here because it does not fix anything.

Mike, do you see these deadlocks with 3.12.*-rt11 as well?

Sebastian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/