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Date: Fri, 14 Sep 2012 20:28:47 +0800 From: Fengguang Wu <fengguang.wu@...el.com> To: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> Cc: paulmck@...ux.vnet.ibm.com, jack@...e.cz, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>, "rusty@...tcorp.com.au" <rusty@...tcorp.com.au>, Peter Zijlstra <peterz@...radead.org>, Tejun Heo <tj@...nel.org>, Michael Wang <wangyun@...ux.vnet.ibm.com> Subject: Re: WARNING: at kernel/rcutree.c:1558 rcu_do_batch+0x386/0x3a0(), during CPU hotplug On Fri, Sep 14, 2012 at 05:48:20PM +0530, Srivatsa S. Bhat wrote: > On 09/14/2012 05:17 PM, Fengguang Wu wrote: > > On Thu, Sep 13, 2012 at 02:05:17PM +0530, Srivatsa S. Bhat wrote: > >> On 09/12/2012 06:06 PM, Srivatsa S. Bhat wrote: > >>> On 07/19/2012 10:45 PM, Paul E. McKenney wrote: > >>>> On Thu, Jul 19, 2012 at 05:39:30PM +0530, Srivatsa S. Bhat wrote: > >>>>> Hi Paul, > >>>>> > >>>>> While running a CPU hotplug stress test on v3.5-rc7+ > >>>>> (mainline commit 8a7298b7805ab) I hit this warning. > >>>>> I haven't tried to debug this yet... > >>>>> > >>>>> Line number 1550 maps to: > >>>>> > >>>>> WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); > >>>>> > >>>>> inside rcu_do_batch(). > >>>> > >>>> Hello, Srivatsa, > >>>> > >>>> I believe that you need commit a16b7a69 (Prevent __call_rcu() from > >>>> invoking RCU core on offline CPUs), which is currently in -tip, queued > >>>> for 3.6. Please see below for the patch. > >>>> > >>>> Does this help? > >>>> > >>> > >>> Hi Paul, > >>> > >>> I am hitting the cpu_is_offline() warning in rcu_do_batch() (see 2 of the > >>> examples below) occasionally while testing CPU hotplug on Thomas' smp/hotplug > >>> branch in -tip. It does contain the commit that you had mentioned above. > >>> > >> > >> I also hit some writeback related problems during some of these runs. But I was > >> not able to reproduce them after that occurrence. (Adding relevant people to CC.) > >> > >> I hit the divide error shown below during the CPU hotplug test run, and the general > > > > I've hit the divide error before. And I'm not luckier than you in > > reproducing the bug. I tempt to add a test as the workaround: > > > > Hi Fengguang, > First of all, thanks for taking a look! > > I just hit it today during my testing again! See below for the stack-traces.. > > > + if (WARN_ON(!denominator)) > > + return dirty; > > Yep, I am going to try this out next and see if the denominator really became 0. OK, thanks for the testing! > I went through the code and I didn't find anything wrong with it. It looks pretty > good (the denominator sanity checking part). Hmm... Yeah, looks so.. > > btw, any chance you may share the CPU hotplug test scripts? > > It'd be a valuable addition to my 0day boot test system. > > > > Sure, I was using a very simple script that does offline/online in sequence. That's all. > Please find it below. Note that adding a breather between the hotplug operations (like > adding sleep as shown below) has the potential to expose different bugs than the normal > stress test (no sleeps between subsequent operations). So both cases are useful to test. > For example, with the sleep, I hit this divide error with higher probability, whereas > without the sleep (stress test) I hit the rcu_do_batch warning more often. > > (And on a slightly different note, when x86 supports CPU 0 hotplug (today it doesn't), > you can use i = 0 instead of i = 1 in the loop. I believe that code is already in -tip). Thank you very much for the script and the detailed notes!! Thanks, Fengguang > > CPU hotplug test script > ----------------------- > #! /bin/bash > > NUMBER_OF_CPUS=`ls -d /sys/devices/system/cpu/cpu[0-9]* | wc -l` > > cd /sys/devices/system/cpu > > while [ 1 ] > do > for ((i=1; i < NUMBER_OF_CPUS; i++)) > do > sleep 1; > state=`cat cpu$i/online` > if [ $state -eq 0 ] > then > echo 1 > cpu$i/online > else > echo 0 > cpu$i/online > fi > done > done > > > >> protection fault subsequently, while trying to shutdown the machine after the test. > > > > Dumps from the divide error and general protection fault in today's testing: > > > [ 4831.353623] SMP alternatives: lockdep: fixing up alternatives > [ 4831.359465] smpboot: Booting Node 1 Processor 13 APIC 0x13 > [ 4833.028342] SMP alternatives: lockdep: fixing up alternatives > [ 4833.034188] smpboot: Booting Node 1 Processor 14 APIC 0x15 > [ 4835.693836] SMP alternatives: lockdep: fixing up alternatives > [ 4835.699609] smpboot: Booting Node 1 Processor 15 APIC 0x17 > [ 4843.142309] Broke affinity for irq 77 > [ 4843.147605] smpboot: CPU 1 is now offline > [ 4843.155885] CPU 9 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4844.379459] Broke affinity for irq 80 > [ 4844.384569] smpboot: CPU 2 is now offline > [ 4844.392111] CPU 10 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4845.810713] smpboot: CPU 3 is now offline > [ 4845.821409] CPU 11 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4848.710692] Broke affinity for irq 74 > [ 4848.716063] smpboot: CPU 4 is now offline > [ 4848.721781] CPU 5 MCA banks CMCI:6 CMCI:8 > [ 4848.726440] CPU 12 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4855.990349] smpboot: CPU 5 is now offline > [ 4855.997251] CPU 6 MCA banks CMCI:6 CMCI:8 > [ 4856.002002] CPU 13 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4859.198420] smpboot: CPU 6 is now offline > [ 4859.205217] CPU 7 MCA banks CMCI:6 CMCI:8 > [ 4859.209858] CPU 14 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4861.202261] smpboot: CPU 7 is now offline > [ 4861.211009] CPU 12 MCA banks CMCI:6 CMCI:8 > [ 4861.215403] CPU 15 MCA banks CMCI:2 CMCI:3 CMCI:5 > [ 4863.210557] smpboot: CPU 8 is now offline > [ 4890.536087] divide error: 0000 [#1] SMP > [ 4890.540047] Modules linked in: ipv6 cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf fuse loop dm_mod iTCO_wdt iTCO_vendor_support coretemp kvm_intel kvm crc32c_intel microcode cdc_ether usbnet i2c_i801 mii tpm_tis pcspkr ioatdma i7core_edac tpm serio_raw i2c_core bnx2 shpchp lpc_ich mfd_core edac_core pci_hotplug dca tpm_bios sg rtc_cmos button uhci_hcd ehci_hcd usbcore usb_common sd_mod crc_t10dif edd ext3 mbcache jbd fan processor mptsas mptscsih mptbase scsi_transport_sas scsi_mod thermal thermal_sys hwmon > [ 4890.540047] CPU 9 > [ 4890.540047] Pid: 2243, comm: flush-8:0 Not tainted 3.6.0-rc1-tglx-hotplug-0.0.0.28.36b5ec9-default #1 IBM IBM System x -[7870C4Q]-/68Y8033 > [ 4890.540047] RIP: 0010:[<ffffffff811276f6>] [<ffffffff811276f6>] bdi_dirty_limit+0x66/0xc0 > [ 4890.540047] RSP: 0018:ffff8808d3e1fcc0 EFLAGS: 00010202 > [ 4890.540047] RAX: 0000000000000000 RBX: 00000000001a80c4 RCX: 28f5c28f5c28f5c3 > [ 4890.540047] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > [ 4890.540047] RBP: ffff8808d3e1fce0 R08: 0000000000000010 R09: 0000000000000000 > [ 4890.540047] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8808d3d80e20 > [ 4890.540047] R13: ffff8808d3d80e20 R14: ffff8808d3d811a0 R15: 0000000000000000 > [ 4890.540047] FS: 0000000000000000(0000) GS:ffff8808ddd40000(0000) knlGS:0000000000000000 > [ 4890.540047] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 4890.540047] CR2: ffffffffff600400 CR3: 0000000001a0c000 CR4: 00000000000007e0 > [ 4890.540047] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 4890.540047] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > [ 4890.540047] Process flush-8:0 (pid: 2243, threadinfo ffff8808d3e1e000, task ffff8808d4060000) > [ 4890.540047] Stack: > [ 4890.540047] 0001000000000000 0000000000000000 ffff8808d3d80e20 fffffffffffffff7 > [ 4890.540047] ffff8808d3e1fd10 ffffffff811ae95c 0000000000350189 00000000001a80c4 > [ 4890.540047] 0000000000000000 0000000000000000 ffff8808d3e1fdc0 ffffffff811b0620 > [ 4890.540047] Call Trace: > [ 4890.540047] [<ffffffff811ae95c>] over_bground_thresh+0x7c/0x90 > [ 4890.540047] [<ffffffff811b0620>] wb_do_writeback+0x170/0x310 > [ 4890.540047] [<ffffffff811b08eb>] bdi_writeback_thread+0x12b/0x420 > [ 4890.540047] [<ffffffff811b07c0>] ? wb_do_writeback+0x310/0x310 > [ 4890.540047] [<ffffffff8106deae>] kthread+0xde/0xf0 > [ 4890.540047] [<ffffffff814c6184>] kernel_thread_helper+0x4/0x10 > [ 4890.540047] [<ffffffff814bc1f0>] ? retint_restore_args+0x13/0x13 > [ 4890.540047] [<ffffffff8106ddd0>] ? __init_kthread_worker+0x70/0x70 > [ 4890.540047] [<ffffffff814c6180>] ? gs_change+0x13/0x13 > [ 4890.540047] Code: 28 5c 8f c2 f5 28 8b 7d e0 48 89 c6 48 0f af f3 48 c1 ee 02 48 89 f0 48 f7 e1 48 89 d6 31 d2 48 c1 ee 02 48 0f af 75 e8 48 89 f0 <48> f7 f7 41 8b 94 24 74 02 00 00 48 0f af d3 48 89 c7 48 c1 ea > [ 4890.540047] RIP [<ffffffff811276f6>] bdi_dirty_limit+0x66/0xc0 > [ 4890.540047] RSP <ffff8808d3e1fcc0> > [ 4890.805627] ---[ end trace 3bdb61d99b220aeb ]--- > [ 4890.818925] Broke affinity for irq 76 > [ 4890.823921] smpboot: CPU 9 is now offline > [ 4900.238238] general protection fault: 0000 [#2] SMP > [ 4900.242203] Modules linked in: ipv6 cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf fuse loop dm_mod iTCO_wdt iTCO_vendor_support coretemp kvm_intel kvm crc32c_intel microcode cdc_ether usbnet i2c_i801 mii tpm_tis pcspkr ioatdma i7core_edac tpm serio_raw i2c_core bnx2 shpchp lpc_ich mfd_core edac_core pci_hotplug dca tpm_bios sg rtc_cmos button uhci_hcd ehci_hcd usbcore usb_common sd_mod crc_t10dif edd ext3 mbcache jbd fan processor mptsas mptscsih mptbase scsi_transport_sas scsi_mod thermal thermal_sys hwmon > [ 4900.248087] CPU 13 > [ 4900.248087] Pid: 0, comm: swapper/13 Tainted: G D 3.6.0-rc1-tglx-hotplug-0.0.0.28.36b5ec9-default #1 IBM IBM System x -[7870C4Q]-/68Y8033 > [ 4900.248087] RIP: 0010:[<ffffffff810843d7>] [<ffffffff810843d7>] try_to_wake_up+0x57/0x2f0 > [ 4900.248087] RSP: 0018:ffff88117fd43d30 EFLAGS: 00010002 > [ 4900.248087] RAX: 6b6b6b6b6b6b6b6b RBX: 000000000000000f RCX: 000000006b6b6b6b > [ 4900.248087] RDX: 000000006b6c6b6b RSI: ffffffff817a7fbf RDI: ffff8808d40607f0 > [ 4900.248087] RBP: ffff88117fd43d70 R08: 0000000000000002 R09: 0000000000000001 > [ 4900.248087] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8808d4060000 > [ 4900.248087] R13: 000000006b6b6b6b R14: ffff8808d3d80e20 R15: 0000000000000000 > [ 4900.248087] FS: 0000000000000000(0000) GS:ffff88117fd40000(0000) knlGS:0000000000000000 > [ 4900.248087] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 4900.248087] CR2: 00007f472ef5f068 CR3: 0000000001a0c000 CR4: 00000000000007e0 > [ 4900.248087] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 4900.248087] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > [ 4900.248087] Process swapper/13 (pid: 0, threadinfo ffff8808d762e000, task ffff8808d7630000) > [ 4900.248087] Stack: > [ 4900.248087] 0000000000000246 ffff8808d40607f0 0000000000000286 ffff8808d762ffd8 > [ 4900.248087] ffff8808d3d80e20 ffff8808d3d811a0 ffff8808d3d80e20 ffffffff8113d970 > [ 4900.248087] ffff88117fd43d80 ffffffff810846a0 ffff88117fd43db0 ffffffff8113da22 > [ 4900.248087] Call Trace: > [ 4900.248087] <IRQ> > [ 4900.248087] [<ffffffff8113d970>] ? bdi_init+0x270/0x270 > [ 4900.248087] [<ffffffff810846a0>] wake_up_process+0x10/0x20 > [ 4900.248087] [<ffffffff8113da22>] wakeup_timer_fn+0xb2/0x1c0 > [ 4900.248087] [<ffffffff810557db>] call_timer_fn+0xcb/0x240 > [ 4900.248087] [<ffffffff81055710>] ? detach_if_pending+0x150/0x150 > [ 4900.248087] [<ffffffff8113d970>] ? bdi_init+0x270/0x270 > [ 4900.248087] [<ffffffff81056f75>] run_timer_softirq+0x1c5/0x2c0 > [ 4900.248087] [<ffffffff8104dc79>] __do_softirq+0x159/0x400 > [ 4900.248087] [<ffffffff814c627c>] call_softirq+0x1c/0x30 > [ 4900.248087] [<ffffffff810044f5>] do_softirq+0x95/0xd0 > [ 4900.248087] [<ffffffff8104d745>] irq_exit+0xe5/0x100 > [ 4900.248087] [<ffffffff81028df9>] smp_apic_timer_interrupt+0x69/0xa0 > [ 4900.248087] [<ffffffff814c5aef>] apic_timer_interrupt+0x6f/0x80 > [ 4900.248087] <EOI> > [ 4900.248087] [<ffffffff812db3d3>] ? intel_idle+0xc3/0x170 > [ 4900.248087] [<ffffffff812db3d7>] ? intel_idle+0xc7/0x170 > [ 4900.248087] [<ffffffff812db3d3>] ? intel_idle+0xc3/0x170 > [ 4900.248087] [<ffffffff813b1937>] cpuidle_enter+0x17/0x20 > [ 4900.248087] [<ffffffff813b1952>] cpuidle_enter_state+0x12/0x50 > [ 4900.248087] [<ffffffff813b2403>] cpuidle_idle_call+0x133/0x260 > [ 4900.248087] [<ffffffff8100b1f5>] cpu_idle+0x95/0xf0 > [ 4900.248087] [<ffffffff814b1819>] start_secondary+0x85/0x8c > [ 4900.248087] Code: 31 ed 48 89 c7 48 89 45 c8 e8 46 72 43 00 48 89 45 d0 49 8b 04 24 85 c3 0f 84 02 02 00 00 45 8b 6c 24 2c 49 8b 44 24 08 45 85 ed <44> 8b 70 18 74 75 8b 1d dd ea 9d 00 85 db 0f 85 2d 02 00 00 49 > [ 4900.248087] RIP [<ffffffff810843d7>] try_to_wake_up+0x57/0x2f0 > [ 4900.248087] RSP <ffff88117fd43d30> > [ 4900.248087] ---[ end trace 3bdb61d99b220aec ]--- > [ 4900.248087] Kernel panic - not syncing: Fatal exception in interrupt > > -- 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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