RCU stall and the system boot hang with nfsroot

[Aaron Ma]

Hi, Paul:
I found the linux-stable-4.1.15 with rt15 patches boot hang sometimes.
Hardware is Grantley-EP and WildcatPass.
No response by sysrq.

Did you found any issue about this? Or how can I address this issue?

Attached kernel config.

Thanks,
Pengyu

xhci_hcd 0000:00:14.0: cache line size of 32 is not supported
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 15 ports detected
xhci_hcd 0000:00:14.0: xHCI Host Controller
xhci_hcd 0000:00:14.0: new USB bus registered, assigned bus number 2
hub 2-0:1.0: USB hub found
hub 2-0:1.0: 6 ports detected
initcall xhci_pci_init+0x0/0x44 returned 0 after 306571 usecs
calling  ehci_hcd_init+0x0/0x5d @ 1
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
initcall ehci_hcd_init+0x0/0x5d returned 0 after 5695 usecs
calling  ehci_pci_init+0x0/0x69 @ 1
ehci-pci: EHCI PCI platform driver
ehci-pci 0000:00:1a.0: enabling bus mastering
ehci-pci 0000:00:1a.0: EHCI Host Controller
ehci-pci 0000:00:1a.0: new USB bus registered, assigned bus number 3
ehci-pci 0000:00:1a.0: debug port 2
ehci-pci 0000:00:1a.0: cache line size of 32 is not supported
ehci-pci 0000:00:1a.0: irq 18, io mem 0x91d02000
cfg80211: Calling CRDA to update world regulatory domain
cfg80211: Calling CRDA to update world regulatory domain
cfg80211: Calling CRDA to update world regulatory domain
cfg80211: Calling CRDA to update world regulatory domain
cfg80211: Calling CRDA to update world regulatory domain
cfg80211: Calling CRDA to update world regulatory domain
cfg80211: Exceeded CRDA call max attempts. Not calling CRDA
INFO: rcu_preempt detected stalls on CPUs/tasks:
    18: (0 ticks this GP) idle=284/0/0 softirq=0/0 fqs=0
    (detected by 12, t=26002 jiffies, g=5351, c=5350, q=451332)
Task dump for CPU 18:
swapper/18      R  running task        0     0      1 0x00200000
 ffffffff814946a7 ffff88045fbc7e58 ffffffff814f42f7 0000000000000004
 0000000000000004 ffff8804663e0f60 ffffffff820dc5c0 ffff88045fbc7ea8
 ffffffff8181fca5 0000000000000000 0000000000000000 0000000000000046
Call Trace:
 [<ffffffff814946a7>] ? debug_smp_processor_id+0x17/0x20
 [<ffffffff814f42f7>] ? intel_idle+0x137/0x140
 [<ffffffff8181fca5>] ? cpuidle_enter_state+0x65/0x3e0
 [<ffffffff81820057>] ? cpuidle_enter+0x17/0x20
 [<ffffffff810a856d>] ? cpu_startup_entry+0x33d/0x630
 [<ffffffff8103cf6e>] ? start_secondary+0x12e/0x140
rcu_preempt kthread starved for 26002 jiffies!
INFO: rcu_preempt detected stalls on CPUs/tasks:
    18: (0 ticks this GP) idle=326/0/0 softirq=0/0 fqs=1
    (detected by 67, t=104007 jiffies, g=5351, c=5350, q=451332)
Task dump for CPU 18:
swapper/18      R  running task        0     0      1 0x00200000
 ffffffff814946a7 ffff88045fbc7e58 ffffffff814f42f7 0000000000000004
 0000000000000004 ffff8804663e0f60 ffffffff820dc5c0 ffff88045fbc7ea8
 ffffffff8181fca5 0000000000000000 0000000000000000 0000000000000046
Call Trace:
 [<ffffffff814946a7>] ? debug_smp_processor_id+0x17/0x20
 [<ffffffff814f42f7>] ? intel_idle+0x137/0x140
 [<ffffffff8181fca5>] ? cpuidle_enter_state+0x65/0x3e0
 [<ffffffff81820057>] ? cpuidle_enter+0x17/0x20
 [<ffffffff810a856d>] ? cpu_startup_entry+0x33d/0x630
 [<ffffffff8103cf6e>] ? start_secondary+0x12e/0x140
rcu_preempt kthread starved for 78005 jiffies!
INFO: rcu_preempt detected stalls on CPUs/tasks:
    18: (0 ticks this GP) idle=35c/0/0 softirq=0/0 fqs=0
    (detected by 62, t=26002 jiffies, g=5352, c=5351, q=451332)
Task dump for CPU 18:
swapper/18      R  running task        0     0      1 0x00200000
 ffffffff814946a7 ffff88045fbc7e58 ffffffff814f42f7 0000000000000004
 0000000000000004 ffff8804663e0f60 ffffffff820dc5c0 ffff88045fbc7ea8
 ffffffff8181fca5 0000000000000000 0000000000000000 0000000000000046
Call Trace:
 [<ffffffff814946a7>] ? debug_smp_processor_id+0x17/0x20
 [<ffffffff814f42f7>] ? intel_idle+0x137/0x140
 [<ffffffff8181fca5>] ? cpuidle_enter_state+0x65/0x3e0
 [<ffffffff81820057>] ? cpuidle_enter+0x17/0x20
 [<ffffffff810a856d>] ? cpu_startup_entry+0x33d/0x630
 [<ffffffff8103cf6e>] ? start_secondary+0x12e/0x140
rcu_preempt kthread starved for 26002 jiffies!
perf interrupt took too long (2575 > 2500), lowering
kernel.perf_event_max_sample_rate to 50000
INFO: task swapper/0:1 blocked for more than 120 seconds.
      Not tainted 4.1.15-rt13-WR8.0.0.0_preempt-rt+ #25
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
swapper/0       D ffff880453547a18     0     1      0 0x00000000
 ffff880453547a18 ffff880851aa8000 000000000000d7a0 ffff88045f604ba0
 ffff880851aa8000 ffff8804535479e8 ffffffff814946a7 ffff880453547a08
 ffff880453548000 ffff880851aa8000 ffff880453547a68 ffff8804663ce500
Call Trace:
 [<ffffffff814946a7>] ? debug_smp_processor_id+0x17/0x20
 [<ffffffff81b60bff>] schedule+0x3f/0xd0
 [<ffffffff81b62c89>] schedule_timeout+0x189/0x3f0
 [<ffffffff810e8f10>] ? timer_cpu_notify+0x190/0x190
 [<ffffffff810eaac2>] msleep+0x42/0x50
 [<ffffffff81759bd6>] ehci_run+0xf6/0x1d0
 [<ffffffff8174329d>] usb_add_hcd+0x2dd/0x810
 [<ffffffff817551de>] usb_hcd_pci_probe+0x33e/0x490
 [<ffffffff81761626>] ehci_pci_probe+0x36/0x40
 [<ffffffff814bfe52>] local_pci_probe+0x42/0xa0
 [<ffffffff814bfda2>] ? pci_match_device+0xf2/0x120
 [<ffffffff814c1199>] pci_device_probe+0xe9/0x150
 [<ffffffff815cf861>] driver_probe_device+0x181/0x310
 [<ffffffff815cfacb>] __driver_attach+0x9b/0xa0
 [<ffffffff815cfa30>] ? __device_attach+0x40/0x40
 [<ffffffff815cd683>] bus_for_each_dev+0x73/0xb0
 [<ffffffff815cf24e>] driver_attach+0x1e/0x20
 [<ffffffff815cee78>] bus_add_driver+0x188/0x240
 [<ffffffff8239ec18>] ? ehci_hcd_init+0x5d/0x5d
 [<ffffffff815d09e4>] driver_register+0x64/0xf0
 [<ffffffff814bf66a>] __pci_register_driver+0x8a/0x90
 [<ffffffff8239ec7f>] ehci_pci_init+0x67/0x69
 [<ffffffff8100045b>] do_one_initcall+0x12b/0x1c0
 [<ffffffff8235615e>] kernel_init_freeable+0x1f9/0x2c0
 [<ffffffff810b26c7>] ? trace_hardirqs_on_caller+0xe7/0x240
 [<ffffffff810b282d>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffff81b641fb>] ? _raw_spin_unlock_irq+0x3b/0x80
 [<ffffffff81087f5c>] ? finish_task_switch+0x9c/0x150
 [<ffffffff81087f1d>] ? finish_task_switch+0x5d/0x150
 [<ffffffff814946a7>] ? debug_smp_processor_id+0x17/0x20
 [<ffffffff81b547a0>] ? rest_init+0x140/0x140
 [<ffffffff81b547ae>] kernel_init+0xe/0xf0
 [<ffffffff81b652a2>] ret_from_fork+0x42/0x70
 [<ffffffff81b547a0>] ? rest_init+0x140/0x140

Attachment: config-stable-rt
Description: Binary data