i.MX6 cpufreq : rcu_sched kthread starved

[Russell King - ARM Linux]

On Thu, Jun 11, 2015 at 10:48:31AM +0200, Jean-Michel Hautbois wrote:
> [  388.902571] INFO: rcu_sched detected stalls on CPUs/tasks: { 1}
> (detected by 0, t=2102 jiffies, g=7088, c=7087, q=34)
> [  388.913334] Task dump for CPU 1:
> [  388.916588] irq/298-IC PP   R running      0    46      2 0x00000002
> [  388.923016] Backtrace:
> [  388.925541] [<8000cbc0>] (vfp_double_ftoui) from [<807fd2c8>]
> (schedule+0x4c/0xa4)

This does not look very good.  If vfp_double_ftoui really is being called
from this path, then that means you're trying to use VFP inside the
kernel, and that's not permitted.

> [  392.127701] CPU: 0 PID: 25 Comm: kworker/0:1 Tainted: G    B    C
>    4.0.5 #49

This also tells me that your kernel has thrown a bad_page() exception,
and you have modules from drivers/staging loaded - so it's possible
that the problem you're seeing here is caused by either an unstable
staging module, or whatever caused the bad_page() exception.

Always investigate the first error first...

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