On Wed, Sep 26, 2012 at 04:15:01PM +0800, Fengguang Wu wrote:
> On Tue, Sep 25, 2012 at 09:34:45PM -0700, Paul E. McKenney wrote:
> > On Wed, Sep 26, 2012 at 12:22:37PM +0800, Fengguang Wu wrote:
> > > On Tue, Sep 25, 2012 at 08:07:01AM -0700, Paul E. McKenney wrote:
> > > > On Tue, Sep 25, 2012 at 07:19:38PM +0800, Fengguang Wu wrote:
> > > > > Hi Paul,
> > > > >
> > > > > I've just bisected down one RCU stall problem:
> > > > >
> > > > > [ 12.035785] pktgen: Packet Generator for packet performance
> > > > > testing. Version: 2.74
> > > > > [ 12.435439] atkbd: probe of serio0 rejects match -19
> > > > > [ 111.700160] INFO: rcu_preempt detected stalls on CPUs/tasks: { 1}
> > > > > (detected by 0, t=10002 jiffies)
> > > > > [ 111.700171] Pid: 0, comm: swapper/0 Not tainted
> > > > > 3.6.0-rc5-00004-gda10491 #1
> > > > > [ 111.700178] Call Trace:
> > > > > [ 111.700475] [<c10c3c84>] rcu_check_callbacks+0x544/0x570
> > > > > [ 111.700538] [<c1075e86>] update_process_times+0x36/0x70
> > > > > [ 111.700547] [<c10a6267>] tick_sched_timer+0x57/0xc0
> > > > > [ 111.700552] [<c108758a>] __run_hrtimer.isra.31+0x4a/0xc0
> > > > > [ 111.700557] [<c10a6210>] ? tick_nohz_handler+0xf0/0xf0
> > > > > [ 111.700559] [<c1088155>] hrtimer_interrupt+0xf5/0x290
> > > > > [ 111.700562] [<c1091cb8>] ? sched_clock_idle_wakeup_event+0x18/0x20
> > > > > [ 111.700565] [<c10a6399>] ? tick_nohz_stop_idle+0x39/0x40
> > > > > [ 111.700572] [<c104f56f>] smp_apic_timer_interrupt+0x4f/0x80
> > > > > [ 111.700587] [<c1753636>] apic_timer_interrupt+0x2a/0x30
> > > > > [ 111.700593] [<c10565b5>] ? native_safe_halt+0x5/0x10
> > > > > [ 111.700599] [<c1039f89>] default_idle+0x29/0x50
> > > > > [ 111.700601] [<c103a958>] cpu_idle+0x68/0xb0
> > > > > [ 111.700609] [<c16f2ff7>] rest_init+0x67/0x70
> > > > > [ 111.700627] [<c1af7929>] start_kernel+0x2ea/0x2f0
> > > > > [ 111.700629] [<c1af7474>] ? repair_env_string+0x51/0x51
> > > > > [ 111.700631] [<c1af72a2>] i386_start_kernel+0x78/0x7d
> > > > > [ 127.040302] bus: 'serio': driver_probe_device: matched device
> > > > > serio0 with driver atkbd
> > > > > [ 127.041308] CPA self-test:
> > > > >
> > > > > to this commit:
> > > > >
> > > > > commit 06ae115a1d551cd952d80df06eaf8b5153351875
> > > > > Author: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> > > > > Date: Sun Aug 14 15:56:54 2011 -0700
> > > > >
> > > > > rcu: Avoid having just-onlined CPU resched itself when RCU is idle
> > > >
> > > > Interesting. Of course the stack is from the CPU that detected the
> > > > problem rather than the problematic CPU. ;-)
> > > >
> > > > Could you please try the following patch?
> > >
> > > Paul, thanks for the quick fix! However it may still stall sometimes.
> > > Attached are 3 dmesgs with the stalls.
> >
> > Do you have c96ea7cf from -rcu applied? Corresponding patch is below.
>
> Nope. I did try linux-next first however the first patch cannot apply
> at all. And I don't know which of the many -rcu branches to work on ;-)
I would suggest rcu/next.2012.09.25b for the moment.
But could you also please send your .config file and a description of
the workload you are running?
Thanx, Paul
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