Re: Linux 4.9-rcX: rcu_preempt detected stalls on CPUs/tasks messages

[Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>]

On 05.11.2016 23:38, Gabriel C wrote:
> Hello ,
>
>
> I've tested 4.9-rcX and Linus git tree and have on this box the following messages :
>
> .....
>
> Nov 05 20:26:40 zwerg kernel: INFO: rcu_preempt detected stalls on CPUs/tasks:
> Nov 05 20:26:40 zwerg kernel:         Tasks blocked on level-0 rcu_node (CPUs 0-15): P0
> Nov 05 20:26:40 zwerg kernel:         (detected by 8, t=60002 jiffies, g=2426, c=2425, q=789)
> Nov 05 20:26:40 zwerg kernel: swapper/0       R  running task        0     0      0 0x00200000
> Nov 05 20:26:40 zwerg kernel:  0000000000000000 ffff88043fc0c6c0 ffffffff810ca25e 0000000000000004
> Nov 05 20:26:40 zwerg kernel:  0000000000000002 0000000000000003 0000000000000010 ffffffff814b936f
> Nov 05 20:26:40 zwerg kernel:  ffff88043fc1d600 ffffffff81893f00 0000000000000003 ffffffff81893de0
> Nov 05 20:26:40 zwerg kernel: Call Trace:
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff810ca25e>] ? __tick_broadcast_oneshot_control+0x5e/0x220
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff814b936f>] ? intel_idle+0xef/0xfe
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff813d3b45>] ? cpuidle_enter_state+0x125/0x200
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff81096e0f>] ? cpu_startup_entry+0x13f/0x230
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff818e9e69>] ? start_kernel+0x428/0x430
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff818e9120>] ? early_idt_handler_array+0x120/0x120
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff818e937a>] ? x86_64_start_kernel+0xef/0xfe
> Nov 05 20:26:40 zwerg kernel: swapper/0       R  running task        0     0      0 0x00200000
> Nov 05 20:26:40 zwerg kernel:  0000000000000000 ffff88043fc0c6c0 ffffffff810ca25e 0000000000000004
> Nov 05 20:26:40 zwerg kernel:  0000000000000002 0000000000000003 0000000000000010 ffffffff814b936f
> Nov 05 20:26:40 zwerg kernel:  ffff88043fc1d600 ffffffff81893f00 0000000000000003 ffffffff81893de0
> Nov 05 20:26:40 zwerg kernel: Call Trace:
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff810ca25e>] ? __tick_broadcast_oneshot_control+0x5e/0x220
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff814b936f>] ? intel_idle+0xef/0xfe
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff813d3b45>] ? cpuidle_enter_state+0x125/0x200
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff81096e0f>] ? cpu_startup_entry+0x13f/0x230
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff818e9e69>] ? start_kernel+0x428/0x430
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff818e9120>] ? early_idt_handler_array+0x120/0x120
> Nov 05 20:26:40 zwerg kernel:  [<ffffffff818e937a>] ? x86_64_start_kernel+0xef/0xfe
>
> .....
>
> When I boot to console mode the system seems to work at least when I'm loggen in from tty1.
> Switching to other tty's sometimes works sometimes not.. Starting X makes the box hang.. sddm starts but I
> never get to the logn screen. After some minutes I have to hard reset the box..
>
> Latest tested git kernel is 4.9.0-rc3-00429-g03daa36 , the box is a FUJITSU PRIMERGY TX200 S5.
>
> config used and dmesg can be found there :
>
> http://ftp.frugalware.org/pub/other/people/crazy/kernel/
>
> Best Regards
>
> Gabriel C

Hi,
i'm witnessing stalls as well (with different stack traces though: [1], 
[2], [3], [4]). Silly enough this seems to happen _only_ at my 
university with wifi enabled (works fine with older kernels: tested 
4.8.4 and older ones as they were recent).

Best Regards,
Tobias Klausmann

[1]: https://homepages.thm.de/~tjkl80/dmesg4.txt
[2]: https://homepages.thm.de/~tjkl80/dmesg3.txt
[3]: https://homepages.thm.de/~tjkl80/dmesg2.txt
[4]: https://homepages.thm.de/~tjkl80/dmesg.txt