Date: Mon, 21 Mar 2005 20:20:51 -0800
From: Andrew Morton <akpm@osdl.org>
To: Lee Revell <rlrevell@joe-job.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, cmorgan@alum.wpi.edu,
       paul@linuxaudiosystems.com, Jamie Lokier <jamie@shareable.org>,
       Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Subject: Re: kernel bug: futex_wait hang
Message-Id: <20050321202051.2796660e.akpm@osdl.org>
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References: <1111463950.3058.20.camel@mindpipe>
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Lee Revell <rlrevell@joe-job.com> wrote:
>
> Paul Davis and Chris Morgan have been chasing down a problem with
> xmms_jack and it really looks like this bug, thought to have been fixed
> in 2.6.10, is the culprit.
> 
> http://www.uwsg.iu.edu/hypermail/linux/kernel/0409.0/2044.html
> 
> (for more info google "futex_wait 2.6 hang")
> 
> It's simple to reproduce.  Run JACK and launch xmms with the JACK output
> plugin.  Close XMMS.  The xmms process hangs.  Strace looks like this:
> 
> rlrevell@krustophenia:~$ strace -p 7935
> Process 7935 attached - interrupt to quit
> futex(0xb5341bf8, FUTEX_WAIT, 7939, NULL
> 
> Just like in the above bug report, if xmms is run with
> LD_ASSUME_KERNEL=2.4.19, it works perfectly.
> 
> I have reproduced the bug with 2.6.12-rc1.
> 

iirc we ended up deciding that the futex problems around that time were due
to userspace problems (a version of libc).  But then, there's no discussion
around Seto's patch and it didn't get applied.  So I don't know what
happened to that work - it's all a bit mysterious.

Is this a 100% repeatable hang, or is it some occasional race?
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