Messages in this thread Patch in this message | | | Date | Thu, 13 Sep 2012 14:30:52 +0800 | From | Michael Wang <> | Subject | Re: WARNING: at kernel/rcutree.c:1558 rcu_do_batch+0x386/0x3a0(), during CPU hotplug |
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On 09/12/2012 11:31 PM, Paul E. McKenney wrote: > On Wed, Sep 12, 2012 at 06:06:20PM +0530, 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. >> >> The stack trace suggests that we are not hitting this from the __call_rcu() >> path. So I guess this needs a different fix? > > So there was an interrupt from stop_machine_stop(). Because RCU complained > about offline, I presume that this was on exit from stop_machine_stop(). > (Otherwise, on entry to stop_machine_stop(), the CPU has not yet marked > itself offline, right?) > > So my question is: Why didn't the CPU shut off all interrupts before > coming out of stop_machine_stop()? > > Or am I confused about what is really happening here?
I think Srivatsa may need patch a3716d2e too:
commit a3716d2e5a50a9ed5268ae3d3c2f093968ff236a Author: Paul E. McKenney <paul.mckenney@linaro.org> Date: Thu Jun 21 09:54:10 2012 -0700
rcu: Prevent offline CPUs from executing RCU core code
Earlier versions of RCU invoked the RCU core from the CPU_DYING notifier in order to note a quiescent state for the outgoing CPU. Because the CPU is marked "offline" during the execution of the CPU_DYING notifiers, the RCU core had to tolerate being invoked from an offline CPU. However, commit b1420f1c (Make rcu_barrier() less disruptive) left only tracing code in the CPU_DYING notifier, so the RCU core need no longer execute on offline CPUs. This commit therefore enforces this restriction.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 300aba6..84a6f55 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1892,6 +1892,8 @@ static void rcu_process_callbacks(struct softirq_action *unused) { struct rcu_state *rsp; + if (cpu_is_offline(smp_processor_id())) + return; trace_rcu_utilization("Start RCU core"); for_each_rcu_flavor(rsp) __rcu_process_callbacks(rsp); With out it, the RCU_SOFTIRQ raised before offline won't have a chance to return.
Regards, Michael Wang > > Thanx, Paul > >> Regards, >> Srivatsa S. Bhat >> >> [ 53.882344] smpboot: CPU 7 is now offline >> [ 53.891072] CPU 12 MCA banks CMCI:6 CMCI:8 >> [ 53.895621] CPU 15 MCA banks CMCI:2 CMCI:3 CMCI:5 >> [ 53.914738] Broke affinity for irq 81 >> [ 53.917769] do_IRQ: 8.211 No irq handler for vector (irq -1) >> [ 53.917769] ------------[ cut here ]------------ >> [ 53.917769] WARNING: at kernel/rcutree.c:1558 rcu_do_batch+0x386/0x3a0() >> [ 53.917769] Hardware name: IBM System x -[7870C4Q]- >> [ 53.917769] 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 cdc_ether usbnet ioatdma lpc_ich mfd_core crc32c_intel microcode mii pcspkr i2c_i801 shpchp i2c_core serio_raw bnx2 tpm_tis dca tpm pci_hotplug i7core_edac tpm_bios edac_core 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 >> [ 53.917769] Pid: 47, comm: migration/8 Not tainted 3.6.0-rc1-tglx-hotplug-0.0.0.28.36b5ec9-default #1 >> [ 53.917769] Call Trace: >> [ 53.917769] <IRQ> [<ffffffff810e7806>] ? rcu_do_batch+0x386/0x3a0 >> [ 53.917769] [<ffffffff810e7806>] ? rcu_do_batch+0x386/0x3a0 >> [ 53.917769] [<ffffffff8104338a>] warn_slowpath_common+0x7a/0xb0 >> [ 53.917769] [<ffffffff810433d5>] warn_slowpath_null+0x15/0x20 >> [ 53.917769] [<ffffffff810e7806>] rcu_do_batch+0x386/0x3a0 >> [ 53.917769] [<ffffffff810ac8a0>] ? trace_hardirqs_on_caller+0x70/0x1b0 >> [ 53.917769] [<ffffffff810ac9ed>] ? trace_hardirqs_on+0xd/0x10 >> [ 53.917769] [<ffffffff810e9143>] __rcu_process_callbacks+0x1a3/0x200 >> [ 53.917769] [<ffffffff810e9228>] rcu_process_callbacks+0x88/0x240 >> [ 53.917769] [<ffffffff8104dc79>] __do_softirq+0x159/0x400 >> [ 53.917769] [<ffffffff814c627c>] call_softirq+0x1c/0x30 >> [ 53.917769] [<ffffffff810044f5>] do_softirq+0x95/0xd0 >> [ 53.917769] [<ffffffff8104d745>] irq_exit+0xe5/0x100 >> [ 53.917769] [<ffffffff81003c14>] do_IRQ+0x64/0xe0 >> [ 53.917769] [<ffffffff814bc12f>] common_interrupt+0x6f/0x6f >> [ 53.917769] <EOI> [<ffffffff810cfe7a>] ? stop_machine_cpu_stop+0xda/0x130 >> [ 53.917769] [<ffffffff810cfda0>] ? stop_one_cpu_nowait+0x50/0x50 >> [ 53.917769] [<ffffffff810cfab9>] cpu_stopper_thread+0xd9/0x1b0 >> [ 53.917769] [<ffffffff814bbe4f>] ? _raw_spin_unlock_irqrestore+0x3f/0x80 >> [ 53.917769] [<ffffffff810cf9e0>] ? res_counter_init+0x50/0x50 >> [ 53.917769] [<ffffffff810ac95d>] ? trace_hardirqs_on_caller+0x12d/0x1b0 >> [ 53.917769] [<ffffffff810ac9ed>] ? trace_hardirqs_on+0xd/0x10 >> [ 53.917769] [<ffffffff810cf9e0>] ? res_counter_init+0x50/0x50 >> [ 53.917769] [<ffffffff8106deae>] kthread+0xde/0xf0 >> [ 53.917769] [<ffffffff814c6184>] kernel_thread_helper+0x4/0x10 >> [ 53.917769] [<ffffffff814bc1f0>] ? retint_restore_args+0x13/0x13 >> [ 53.917769] [<ffffffff8106ddd0>] ? __init_kthread_worker+0x70/0x70 >> [ 53.917769] [<ffffffff814c6180>] ? gs_change+0x13/0x13 >> [ 53.917769] ---[ end trace f60a282810c4ce78 ]--- >> [ 54.170634] smpboot: CPU 8 is now offline >> [ 54.192259] NOHZ: local_softirq_pending 200 >> [ 54.197936] smpboot: CPU 9 is now offline >> [ 54.219707] NOHZ: local_softirq_pending 200 >> [ 54.225795] smpboot: CPU 10 is now offline >> >> >> --- >> >> [ 372.482434] smpboot: CPU 11 is now offline >> [ 372.534211] smpboot: CPU 12 is now offline >> [ 372.539786] CPU 13 MCA banks CMCI:6 CMCI:8 >> [ 372.582474] smpboot: CPU 13 is now offline >> [ 372.591006] CPU 14 MCA banks CMCI:6 CMCI:8 >> [ 372.629745] ------------[ cut here ]------------ >> [ 372.633736] WARNING: at kernel/rcutree.c:1558 rcu_do_batch+0x386/0x3a0() >> [ 372.633736] Hardware name: IBM System x -[7870C4Q]- >> [ 372.633736] 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 serio_raw tpm_tis i7core_edac cdc_ether usbnet ioatdma mii lpc_ich pcspkr edac_core mfd_core bnx2 shpchp pci_hotplug i2c_i801 i2c_core dca tpm sg tpm_bios 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 >> [ 372.633736] Pid: 8625, comm: migration/14 Not tainted 3.6.0-rc1-tglx-hotplug-0.0.0.28.36b5ec9-default #1 >> [ 372.633736] Call Trace: >> [ 372.633736] <IRQ> [<ffffffff810e7806>] ? rcu_do_batch+0x386/0x3a0 >> [ 372.633736] [<ffffffff810e7806>] ? rcu_do_batch+0x386/0x3a0 >> [ 372.633736] [<ffffffff8104338a>] warn_slowpath_common+0x7a/0xb0 >> [ 372.633736] [<ffffffff810433d5>] warn_slowpath_null+0x15/0x20 >> [ 372.633736] [<ffffffff810e7806>] rcu_do_batch+0x386/0x3a0 >> [ 372.633736] [<ffffffff810ac8a0>] ? trace_hardirqs_on_caller+0x70/0x1b0 >> [ 372.633736] [<ffffffff810ac9ed>] ? trace_hardirqs_on+0xd/0x10 >> [ 372.633736] [<ffffffff810e9143>] __rcu_process_callbacks+0x1a3/0x200 >> [ 372.633736] [<ffffffff810e9228>] rcu_process_callbacks+0x88/0x240 >> [ 372.633736] [<ffffffff8104dc79>] __do_softirq+0x159/0x400 >> [ 372.633736] [<ffffffff814c627c>] call_softirq+0x1c/0x30 >> [ 372.633736] [<ffffffff810044f5>] do_softirq+0x95/0xd0 >> [ 372.633736] [<ffffffff8104d745>] irq_exit+0xe5/0x100 >> [ 372.633736] [<ffffffff81028df9>] smp_apic_timer_interrupt+0x69/0xa0 >> [ 372.633736] [<ffffffff814c5aef>] apic_timer_interrupt+0x6f/0x80 >> [ 372.633736] <EOI> [<ffffffff810cfe7a>] ? stop_machine_cpu_stop+0xda/0x130 >> [ 372.633736] [<ffffffff810cfda0>] ? stop_one_cpu_nowait+0x50/0x50 >> [ 372.633736] [<ffffffff810cfab9>] cpu_stopper_thread+0xd9/0x1b0 >> [ 372.633736] [<ffffffff814bbe4f>] ? _raw_spin_unlock_irqrestore+0x3f/0x80 >> [ 372.633736] [<ffffffff810cf9e0>] ? res_counter_init+0x50/0x50 >> [ 372.633736] [<ffffffff810ac95d>] ? trace_hardirqs_on_caller+0x12d/0x1b0 >> [ 372.633736] [<ffffffff810ac9ed>] ? trace_hardirqs_on+0xd/0x10 >> [ 372.633736] [<ffffffff810cf9e0>] ? res_counter_init+0x50/0x50 >> [ 372.633736] [<ffffffff8106deae>] kthread+0xde/0xf0 >> [ 372.633736] [<ffffffff814c6184>] kernel_thread_helper+0x4/0x10 >> [ 372.633736] [<ffffffff814bc1f0>] ? retint_restore_args+0x13/0x13 >> [ 372.633736] [<ffffffff8106ddd0>] ? __init_kthread_worker+0x70/0x70 >> [ 372.633736] [<ffffffff814c6180>] ? gs_change+0x13/0x13 >> [ 372.633736] ---[ end trace a4296a31284c846d ]--- >> [ 372.883063] smpboot: CPU 14 is now offline >> [ 372.892721] CPU 15 MCA banks CMCI:6 CMCI:8 >> [ 372.907250] smpboot: CPU 15 is now offline >> [ 372.911545] SMP alternatives: lockdep: fixing up alternatives >> [ 372.917292] SMP alternatives: switching to UP code >> [ 372.941917] SMP alternatives: lockdep: fixing up alternatives >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@vger.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@vger.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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