linux-kernel - Re: Fwd: [BUG] oops in cpufreq driver with AMD Kaveri CPU

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Date:	Tue, 12 Aug 2014 18:39:39 -0500
From:	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
To:	<oleksandr@...alenko.name>
CC:	<viresh.kumar@...aro.org>, LKML <linux-kernel@...r.kernel.org>,
	<linux-pm@...r.kernel.org>
Subject: Re: Fwd: [BUG] oops in cpufreq driver with AMD Kaveri CPU

On 8/12/2014 2:51 PM, Aravind Gopalakrishnan wrote:
>
>
> Hello.
>
> Occasionally I get my machine hung completely. Fortunately, I've got 
> and saved
> oops listing using netconsole before hang, and here it is [1].
>
> Here is little piece of oops from the link above:
>
> ===
> [15051.270461] BUG: unable to handle kernel paging request at 
> 00000000ff5ae8e4
> [15051.271583] IP: [<ffffffff8109ae6e>] srcu_notifier_call_chain+0xe/0x20
> …
> [15051.956205] Call Trace:
> [15051.980641]  [<ffffffff81606085>] ? 
> __cpufreq_notify_transition+0x95/0x1e0
> [15052.005640]  [<ffffffff816081ee>] cpufreq_notify_transition+0x3e/0x70
> [15052.030240]  [<ffffffff816083d8>] 
> cpufreq_freq_transition_begin+0xe8/0x130
> [15052.054522]  [<ffffffff813b8940>] ? ucs2_strncmp+0x70/0x70
> [15052.078208]  [<ffffffff816089bf>] __target_index+0xbf/0x1a0
> [15052.101348]  [<ffffffff81608b9c>] __cpufreq_driver_target+0xfc/0x160
> [15052.124250]  [<ffffffff8160b0d4>] od_check_cpu+0xa4/0xb0
> [15052.146789]  [<ffffffff8160c9ec>] dbs_check_cpu+0x16c/0x1c0
> [15052.168935]  [<ffffffff8160b4dd>] od_dbs_timer+0x11d/0x180
> [15052.190607]  [<ffffffff8108e6ff>] process_one_work+0x17f/0x4c0
> [15052.211825]  [<ffffffff8108f46b>] worker_thread+0x11b/0x3f0
> [15052.232490]  [<ffffffff8108f350>] ? create_and_start_worker+0x80/0x80
> [15052.253127]  [<ffffffff81096479>] kthread+0xc9/0xe0
> [15052.273292]  [<ffffffff810963b0>] ? flush_kthread_worker+0xb0/0xb0
> [15052.293487]  [<ffffffff81793efc>] ret_from_fork+0x7c/0xb0
> [15052.313544]  [<ffffffff810963b0>] ? flush_kthread_worker+0xb0/0xb0
> …
> ===
>
> Also here is my lspci [2] and cpuinfo [3] as well.
>
> Vanilla 3.15.8 and 3.16.0 are affected as well as latest Ubuntu 3.13 
> kernel.
>
> No visible reason to trigger the bug. After hang machine doesn't 
> respond via
> network, there's no disk IO, and also it doesn't respond to pressing power
> button in order to perform soft off.
>
> [1] https://gist.github.com/085af9da81197faf6637
> [2] https://gist.github.com/318ebda5576b099590b8
> [3] https://gist.github.com/9c1307463c7ad6835b2d
>
>

Hi,

I noticed this ping yesterday and tried to reproduce your issue on a 
similar system I have (btw, this is a 'Kabini' processor and not a 
'Kaveri') without success.

/proc/cpuinfo:

processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 22
model           : 0
model name      : AMD Opteron(tm) X2150 APU
stepping        : 1
microcode       : 0x7000106
cpu MHz         : 800.000
cache size      : 2048 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext 
fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc 
extd_apicid aperfmperf eagerfpu pni pclmulqdq monitor ssse3 cx16 sse4_1 
sse4_2 movbe popcnt aes xsave avx f16c lahf_lm cmp_legacy svm extapic 
cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt 
topoext perfctr_nb perfctr_l2 arat xsaveopt hw_pstate proc_feedback npt 
lbrv svm_lock nrip_save tsc_scale flushbyasid decodeassists pausefilter 
pfthreshold bmi1
bogomips        : 3793.19
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: ts ttp tm 100mhzsteps hwpstate [11]

Since the BUG happens on a frequency transition, I tried this-
periodically ramped up the cpu frequency by running a workload to keep 
all cores busy for sometime; And let cpu frequency drop down by killing 
the load.
Repeated this cycle overnight yesterday but did not notice the BUG.
(Using ondemand governor, with uname -r: 3.16-rc4)
(I think you mentioned you were able to reproduce on 3.16. So assuming 
-rc will be affected too)

Are you noticing this BUG when you are running any particular load?
I could help debug effort or test patches to fix issue(whenever 
necessary) if I have some way to reproduce this..

-Aravind
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