WARNING: at kernel/rcutree.c:1558 rcu_do_batch+0x386/0x3a0(), duringCPU hotplug

From: Srivatsa S. Bhat
Date: Wed Sep 12 2012 - 08:36:51 EST


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?

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

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