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Date: Wed, 20 May 2009 22:16:58 -0700 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: Janos Haar <janos.haar@...center.hu> Cc: linux-kernel@...r.kernel.org, neilb@...e.de Subject: Re: Fw: RCU detected CPU 1 stall (t=4295904002/751 jiffies) Pid:902, comm: md1_raid5 On Thu, May 21, 2009 at 06:46:15AM +0200, Janos Haar wrote: > Paul, > > Thank you for your attention. > Yes, the PC makes 2-3 second "pauses" and drop this message again and > again. > If i remove the RCU debugging, the message disappears, but the pauses still > here, and makes 2-3 load on the idle system. > Can i do something? > You suggest to use PREEMPT? (This is a server.) One possibility is that the lock that bitmap_daemon_work() acquires is being held for too long. Another possibility is the list traversal in md_check_recovery() that might loop for a long time if the list were excessively long or could be temporarily tied in a knot. Neil, thoughts? Thanx, Paul > Thank you, > Janos Haar > > ----- Original Message ----- From: "Paul E. McKenney" > <paulmck@...ux.vnet.ibm.com> > To: "Janos Haar" <djani22@...center.hu> > Cc: <linux-kernel@...r.kernel.org> > Sent: Thursday, May 21, 2009 4:50 AM > Subject: Re: Fw: RCU detected CPU 1 stall (t=4295904002/751 jiffies) > Pid:902, comm: md1_raid5 > > >> On Wed, May 20, 2009 at 11:46:07AM +0200, Janos Haar wrote: >>> Hello list, >>> >>> Somebody know, what is this? >>> May 17 23:12:13 gladiator-afth1 kernel: RCU detected CPU 1 stall >>> (t=4295904002/751 jiffies) >>> May 17 23:12:13 gladiator-afth1 kernel: Pid: 902, comm: md1_raid5 Not >>> tainted 2.6.28.10 #1 >>> May 17 23:12:13 gladiator-afth1 kernel: Call Trace: >>> May 17 23:12:13 gladiator-afth1 kernel: <IRQ> [<ffffffff80265395>] ? >>> get_timestamp+0x9/0xf >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff8026854f>] >>> __rcu_pending+0x64/0x1e2 >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff80268703>] >>> rcu_pending+0x36/0x6f >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff8023f546>] >>> update_process_times+0x37/0x5f >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff802504a7>] >>> tick_periodic+0x6e/0x7a >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff802504d4>] >>> tick_handle_periodic+0x21/0x65 >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff8021ad60>] >>> smp_apic_timer_interrupt+0x8f/0xad >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff8020bf1b>] >>> apic_timer_interrupt+0x6b/0x70 >>> May 17 23:12:13 gladiator-afth1 kernel: <EOI> [<ffffffff80820b8f>] ? >>> _spin_unlock_irqrestore+0x13/0x17 >> >> One of the following functions is looping in the kernel. If you are >> running with HZ=250, it has been looping for about three seconds. >> Interrupts are enabled, but preemption must be disabled (perhaps due >> to !CONFIG_PREEMPT). >> >> Thanx, Paul >> >>> May 17 23:12:13 gladiator-afth1 kernel: [<ffffffff80728720>] ? >>> bitmap_daemon_work+0x142/0x3b0 >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff80724c58>] ? >>> md_check_recovery+0x1b/0x45b >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff8071976c>] ? >>> raid5d+0x5d/0x503 >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff80726533>] ? >>> md_thread+0xd5/0xed >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff80248e4a>] ? >>> autoremove_wake_function+0x0/0x38 >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff8072645e>] ? >>> md_thread+0x0/0xed >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff80248d3b>] ? >>> kthread+0x49/0x76 >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff8020c169>] ? >>> child_rip+0xa/0x11 >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff80248cf2>] ? >>> kthread+0x0/0x76 >>> May 17 23:12:18 gladiator-afth1 kernel: [<ffffffff8020c15f>] ? >>> child_rip+0x0/0x11 >>> Neilbrown from the RAID list suggested to ask someone else...(The mail is >>> below.)Thanks,Janos Haar----- Original Message ----- From: "Janos Haar" >>> <janos.haar@...center.hu> >>> To: "Neil Brown" <neilb@...e.de> >>> Cc: <linux-raid@...r.kernel.org> >>> Sent: Tuesday, May 19, 2009 12:30 PM >>> Subject: Re: RCU detected CPU 1 stall (t=4295904002/751 jiffies) Pid: >>> 902, >>> comm: md1_raid5 >>> >>> >>>> >>>> ----- Original Message ----- From: "Neil Brown" <neilb@...e.de> >>>> To: "Janos Haar" <janos.haar@...center.hu> >>>> Cc: <linux-raid@...r.kernel.org> >>>> Sent: Tuesday, May 19, 2009 3:05 AM >>>> Subject: Re: RCU detected CPU 1 stall (t=4295904002/751 jiffies) Pid: >>>> 902, >>>> comm: md1_raid5 >>>> >>>> >>>>> On Tuesday May 19, janos.haar@...center.hu wrote: >>>>>> Hello list, Neil, >>>>>> >>>>>> Somebody can say something about this issue? >>>>>> I am not surprised, if it is hardware related, but this is on a brand >>>>>> new >>>>>> server, so i am looking for a solution... :-) >>>>>> May 17 23:12:13 gladiator-afth1 kernel: RCU detected CPU 1 stall >>>>>> (t=4295904002/751 jiffies) >>>>> >>>>> I have no idea what this means. >>>>> I've occasionally seen this sort of message in early boot then the >>>>> system continued to work perfectly so I figured it was an early-boot >>>>> glitch. I suggest asking someone who understands RCU. >>>>> >>>>>> >>>>>> The entire log is here: >>>>>> http://download.netcenter.hu/bughunt/20090518/messages >>>>>> >>>>>> The system is on the md1, and working, but slowly. >>>>> >>>>> How slowly? Is the slowness due to disk throughput? >>>> >>>> No no, this is a fresh and idle server. >>>> I have configured the disks, raid on another PC, and when it finished, i >>>> have copy up the known good, pre-installed sw pack with old 2.6.18. >>>> This pack is good, tested on many times, and this reports too this issue >>>> on this machine. (first) >>>> I have compiled the 2.6.28.10 on it, it takes about 6 hour! 8-/ >>>> But the 2.6.28.10 reports this too. >>>> >>>> The slowness is not disk based, i think, on idle time if i move the >>>> selector line in mc, this stopps too for some seconds or i can't type in >>>> bash when this happens, and another one RCU message comes to the log... >>>> (It happens periodically, independently of i am doing something or not.) >>>> >>>> I am not sure, it is raid related or not, but the kernel reports only >>>> the >>>> md1_raid5 pid, not another one. >>>> This is why i am asking here first. >>>> >>>> Thanks anyway. :-) >>>> >>>>> Have you tested the individual drives and compared that with the >>>>> array? >>>> >>>> This is a brand new hw, with 4x500GB samsung drive, wich reports no >>>> problem at all by smart. >>>> >>>>> >>>>> >>>>>> If i left the server for 1 day, it will crash without a saved log. >>>>> >>>>> This is a concern! It usually points to some sort of hardware >>>>> problem, but it is very hard to trace. >>>>> Is the power supply rated high enough to support all devices? >>>> >>>> I am using 550W good quality new PS, and the PC uses only 55-65W, >>>> measured. ;-) >>>> (1x core2duo, 4x hdd, nothing more interesting) >>>> >>>>> I cannot think of anything else to suggest .. except start swapping >>>>> components until the problem goes away... >>>> >>>> In this way, i need to start with the motherboard. 8-( >>>> >>>> Thanks a lot, >>>> Janos Haar >>>> >>>>> >>>>> NeilBrown >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>>> the body of a message to majordomo@...r.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> -- >>> 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/ > -- 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/
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