<br><br>On Monday, November 7, 2016, Gautham R Shenoy <<a href="mailto:ego@linux.vnet.ibm.com">ego@linux.vnet.ibm.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Denis,<br>
<br>
On Fri, Nov 04, 2016 at 07:08:38AM -0400, Denis Kirjanov wrote:<br>
<br>
You can provide the config option with which this bug was found in the<br>
change log. I suppose you had enabled CONFIG_DEBUG_PREEMPT.<br>
<br></blockquote><div><br></div>that's why I put the comment <br><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
>     [   67.700897] BUG: using smp_processor_id() in preemptible [00000000] code: cat/7343<br>
>     [   67.700988] caller is .powernv_cpufreq_throttle_<wbr>check+0x2c/0x710<br>
>     [   67.700998] CPU: 13 PID: 7343 Comm: cat Not tainted 4.8.0-rc5-dirty #1<br>
>     [   67.701038] Call Trace:<br>
>     [   67.701066] [c0000007d25b75b0] [c000000000971378] .dump_stack+0xe4/0x150 (unreliable)<br>
>     [   67.701153] [c0000007d25b7640] [c0000000005162e4] .check_preemption_disabled+<wbr>0x134/0x150<br>
>     [   67.701238] [c0000007d25b76e0] [c0000000007b63ac] .powernv_cpufreq_throttle_<wbr>check+0x2c/0x710<br>
>     [   67.701322] [c0000007d25b7790] [c0000000007b6d18] .powernv_cpufreq_target_index+<wbr>0x288/0x360<br>
>     [   67.701407] [c0000007d25b7870] [c0000000007acee4] .__cpufreq_driver_target+<wbr>0x394/0x8c0<br>
>     [   67.701491] [c0000007d25b7920] [c0000000007b22ac] .cpufreq_set+0x7c/0xd0<br>
>     [   67.701565] [c0000007d25b79b0] [c0000000007adf50] .store_scaling_setspeed+0x80/<wbr>0xc0<br>
>     [   67.701650] [c0000007d25b7a40] [c0000000007ae270] .store+0xa0/0x100<br>
>     [   67.701723] [c0000007d25b7ae0] [c0000000003566e8] .sysfs_kf_write+0x88/0xb0<br>
>     [   67.701796] [c0000007d25b7b70] [c0000000003553b8] .kernfs_fop_write+0x178/0x260<br>
>     [   67.701881] [c0000007d25b7c10] [c0000000002ac3cc] .__vfs_write+0x3c/0x1c0<br>
>     [   67.701954] [c0000007d25b7cf0] [c0000000002ad584] .vfs_write+0xc4/0x230<br>
>     [   67.702027] [c0000007d25b7d90] [c0000000002aeef8] .SyS_write+0x58/0x100<br>
>     [   67.702101] [c0000007d25b7e30] [c00000000000bfec] system_call+0x38/0xfc<br>
><br>
> Signed-off-by: Denis Kirjanov <<a href="javascript:;" onclick="_e(event, 'cvml', 'kda@linux-powerpc.org')">kda@linux-powerpc.org</a>><br>
><br>
> v2:  wrap powernv_cpufreq_throttle_<wbr>check()<br>
> as suggested by Gautham R Shenoy<br>
<br>
Looks good otherwise.<br>
<br>
Reviewed-by: Gautham R. Shenoy <<a href="javascript:;" onclick="_e(event, 'cvml', 'ego@linux.vnet.ibm.com')">ego@linux.vnet.ibm.com</a>><br>
<br>
> ---<br>
>  drivers/cpufreq/powernv-<wbr>cpufreq.c | 9 ++++++++-<br>
>  1 file changed, 8 insertions(+), 1 deletion(-)<br>
><br>
> diff --git a/drivers/cpufreq/powernv-<wbr>cpufreq.c b/drivers/cpufreq/powernv-<wbr>cpufreq.c<br>
> index d3ffde8..112e0e2 100644<br>
> --- a/drivers/cpufreq/powernv-<wbr>cpufreq.c<br>
> +++ b/drivers/cpufreq/powernv-<wbr>cpufreq.c<br>
> @@ -647,8 +647,15 @@ static int powernv_cpufreq_target_index(<wbr>struct cpufreq_policy *policy,<br>
>       if (unlikely(rebooting) && new_index != get_nominal_index())<br>
>               return 0;<br>
><br>
> -     if (!throttled)<br>
> +     if (!throttled) {<br>
> +             /*<br>
> +              * we don't want to be preempted while<br>
> +              * checking if the CPU frequency has been throttled<br>
> +              */<br>
> +             preempt_disable();<br>
>               powernv_cpufreq_throttle_<wbr>check(NULL);<br>
> +             preempt_enable();<br>
> +    }<br>
><br>
>       cur_msec = jiffies_to_msecs(get_jiffies_<wbr>64());<br>
><br>
> --<br>
> 1.8.3.1<br>
><br>
<br>
</blockquote>