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From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org,
	LKML <linux-kernel@vger.kernel.org>,
	davidlohr@hp.com, paulus@samba.org, tglx@linutronix.de,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	torvalds@linux-foundation.org, mingo@kernel.org
Subject: Re: Tasks stuck in futex code (in 3.14-rc6)
Date: Thu, 20 Mar 2014 11:03:50 +0530	[thread overview]
Message-ID: <20140320053350.GB30295@linux.vnet.ibm.com> (raw)
In-Reply-To: <20140319170829.GD8557@laptop.programming.kicks-ass.net>

> > Joy,.. let me look at that with ppc in mind.
> 
> OK; so while pretty much all the comments from that patch are utter
> nonsense (what was I thinking), I cannot actually find a real bug.
> 
> But could you try the below which replaces a control dependency with a
> full barrier. The control flow is plenty convoluted that I think the
> control barrier isn't actually valid anymore and that might indeed
> explain the fail.
> 

Unfortunately the patch didnt help. Still seeing tasks stuck

# ps -Ao pid,tt,user,fname,tmout,f,wchan | grep futex
14680 pts/0    root     java         - 0 futex_wait_queue_me
14797 pts/0    root     java         - 0 futex_wait_queue_me
# :> /var/log/messages
# echo t > /proc/sysrq-trigger 
# grep futex_wait_queue_me /var/log/messages | wc -l 
334
#

[ 6904.211478] Call Trace:
[ 6904.211481] [c000000fa1f1b4d0] [0000000000000020] 0x20 (unreliable)
[ 6904.211486] [c000000fa1f1b6a0] [c000000000015208] .__switch_to+0x1e8/0x330
[ 6904.211491] [c000000fa1f1b750] [c000000000702f00] .__schedule+0x360/0x8b0
[ 6904.211495] [c000000fa1f1b9d0] [c000000000147348] .futex_wait_queue_me+0xf8/0x1a0
[ 6904.211500] [c000000fa1f1ba60] [c0000000001486dc] .futex_wait+0x17c/0x2a0
[ 6904.211505] [c000000fa1f1bc10] [c00000000014a614] .do_futex+0x254/0xd80
[ 6904.211510] [c000000fa1f1bd60] [c00000000014b25c] .SyS_futex+0x11c/0x1d0
[ 6904.238874] [c000000fa1f1be30] [c00000000000a0fc] syscall_exit+0x0/0x7c
[ 6904.238879] java            S 00003fff825f6044     0 14682  14076 0x00000080

Is there any other information that I provide that can help?

-- 
Thanks and Regards
Srikar Dronamraju

  parent reply	other threads:[~2014-03-20  5:34 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-19 15:26 Tasks stuck in futex code (in 3.14-rc6) Srikar Dronamraju
2014-03-19 15:47 ` Peter Zijlstra
2014-03-19 16:09   ` Srikar Dronamraju
2014-03-19 17:08   ` Peter Zijlstra
2014-03-19 18:06     ` Davidlohr Bueso
2014-03-20  5:33     ` Srikar Dronamraju [this message]
2014-03-20  5:56       ` Davidlohr Bueso
2014-03-20 10:08         ` Srikar Dronamraju
2014-03-20 15:06           ` Davidlohr Bueso
2014-03-20 16:31         ` Davidlohr Bueso
2014-03-20 20:23           ` Benjamin Herrenschmidt
2014-03-20 16:41         ` Linus Torvalds
2014-03-20 17:18           ` Davidlohr Bueso
2014-03-20 17:42             ` Linus Torvalds
2014-03-20 18:03               ` Davidlohr Bueso
2014-03-20 18:16                 ` Linus Torvalds
2014-03-20 18:36             ` Linus Torvalds
2014-03-20 19:08               ` Davidlohr Bueso
2014-03-20 19:25                 ` Linus Torvalds
2014-03-20 20:20                   ` Davidlohr Bueso
2014-03-20 20:36                     ` Linus Torvalds
2014-03-21  4:55                     ` Srikar Dronamraju
2014-03-21  5:24                       ` Linus Torvalds
2014-03-22  2:27                         ` Srikar Dronamraju
2014-03-22  3:36                           ` Davidlohr Bueso
2014-03-20  7:23       ` Peter Zijlstra
2014-03-19 16:04 ` Linus Torvalds

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