linux-kernel - Re: Deadlocks due to per-process plugging

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: <alpine.LFD.2.02.1207151057010.32033@ionos>
Date:	Sun, 15 Jul 2012 10:59:34 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Jan Kara <jack@...e.cz>
cc:	Jeff Moyer <jmoyer@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Jens Axboe <jaxboe@...ionio.com>, mgalbraith@...e.com
Subject: Re: Deadlocks due to per-process plugging

On Fri, 13 Jul 2012, Jan Kara wrote:
> On Fri 13-07-12 16:25:05, Thomas Gleixner wrote:
> > So the patch below should allow the unplug to take place when blocked
> > on mutexes etc.
>   Thanks for the patch! Mike will give it some testing.

I just found out that this patch will explode nicely when the unplug
code runs into a contended lock. Then we try to block on that lock and
make the rtmutex code unhappy as we are already blocked on something
else.

So no, it's not a solution to the problem. Sigh.

Can you figure out on which lock the stuck thread which did not unplug
due to tsk_is_pi_blocked was blocked?

Thanks,

	tglx
--
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/