Re: [PATCH 0/5] [GIT PULL] updates for tip/tracing/ftrace

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Thu, Mar 19, 2009 at 01:21:47PM -0400, Steven Rostedt wrote:
> 
> I'm still not able to reproduce, but...
> 
> On Thu, 19 Mar 2009, Ingo Molnar wrote:
> 
> > * Ingo Molnar <mingo@elte.hu> wrote:
> > 
> > > these latest ftrace changes caused a lockup on a -tip testsystem:
> > 
> > Note, even with Rusty's offstack-cpumask fix applied (in latest 
> > -tip), i can reproduce a lockup:
> > 

[ . . . ]

> This looks like it is RCU/stop_machine related. The CPU is stuck in
> in stop_machine? I see that rcu_torture is running. Does this go away if 
> you turn off rcu_torture?

Grasping at straws...  Does Lai's rcu_barrier() fix help?

							Thanx, Paul

> -- Steve
> 
> > [   18.620342]  [<ffffffff80294a29>] ? run_workqueue+0x1a0/0x2e2
> > [   18.620342]  [<ffffffff802949d6>] ? run_workqueue+0x14d/0x2e2
> > [   18.620342]  [<ffffffff802ceb5d>] ? stop_cpu+0x0/0x1d1
> > [   18.620342]  [<ffffffff826b4140>] ? early_idt_handler+0x0/0x73
> > [   18.620342]  [<ffffffff80295d1b>] ? worker_thread+0x138/0x14c
> > [   18.620342]  [<ffffffff80299e63>] ? autoremove_wake_function+0x0/0x4f
> > [   18.620342]  [<ffffffff80295be3>] ? worker_thread+0x0/0x14c
> > [   18.620342]  [<ffffffff80299d20>] ? kthread+0x60/0xa0
> > [   18.620342]  [<ffffffff8021606a>] ? child_rip+0xa/0x20
> > [   18.620342]  [<ffffffff8026fd4b>] ? finish_task_switch+0x56/0x180
> > [   18.620342]  [<ffffffff80215a10>] ? restore_args+0x0/0x30
> > [   18.620342]  [<ffffffff80299cc0>] ? kthread+0x0/0xa0
> > [   18.620342]  [<ffffffff80216060>] ? child_rip+0x0/0x20
> > [   64.758749] INFO: RCU detected CPU 0 stall (t=4294710313/40000 jiffies)
> > [   64.758749] Pid: 858, comm: kstop/0 Not tainted 2.6.29-rc8-tip-02638-g1c002f5-dirty #3067
> > 
> > (the hang is real - it lasted overnight without the system ever 
> > managing to boot up.)
> > 
> > Config (note, it's different from the config i sent last) and full 
> > bootlog attached.
> > 
> > 	Ingo
> > 
> --
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