linux-kernel - Re: Tasks stuck in futex code (in 3.14-rc6)

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: <20140319154705.GB8557@laptop.programming.kicks-ass.net>
Date:	Wed, 19 Mar 2014 16:47:05 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	davidlohr@...com, torvalds@...ux-foundation.org,
	tglx@...utronix.de, mingo@...nel.org,
	LKML <linux-kernel@...r.kernel.org>,
	linuxppc-dev@...ts.ozlabs.org, benh@...nel.crashing.org,
	paulus@...ba.org
Subject: Re: Tasks stuck in futex code (in 3.14-rc6)

On Wed, Mar 19, 2014 at 08:56:19PM +0530, Srikar Dronamraju wrote:
> There are 332 tasks all stuck in futex_wait_queue_me().
> I am able to reproduce this consistently.
> 
> Infact I can reproduce this if the java_constraint is either node, socket, system.
> However I am not able to reproduce if java_constraint is set to core.

What's any of that mean?

> I ran git bisect between v3.12 and v3.14-rc6 and found that
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b0c29f79ecea0b6fbcefc999e70f2843ae8306db
> 
> commit b0c29f79ecea0b6fbcefc999e70f2843ae8306db
> Author: Davidlohr Bueso <davidlohr@...com>
> Date:   Sun Jan 12 15:31:25 2014 -0800
> 
> futexes: Avoid taking the hb->lock if there's nothing to wake up
> 
> was the commit thats causing the threads to be stuck in futex.
> 
> I reverted b0c29f79ecea0b6fbcefc999e70f2843ae8306db on top of v3.14-rc6 and confirmed that
> reverting the commit solved the problem.

Joy,.. let me look at that with ppc in mind.
--
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/