Problem with kernel-5.0.3-200.fc29.armv7hl on Raspberry PI 3B/3B+

[William Jacobs]

Yesterday I installed the above referenced kernel on two Raspberry PIs, a 3B+ and a 3B.  I
also installed it on a BeagleBone Black and a Hummingboard2 (nxp i.mx6 Quad CPU).

On the BeagleBone Black and the Hummingboard, no problems at all, so this appears to be
specific to the Raspberry PI platform or CPU.  The Raspberry PI's are both actually
running, but I noticed that top tells me that the load average is 4.0.  But these things
are not actually doing anything.  Top does not show any process using more than 0.7% CPU
and that it tells me that each core is nearly 100% idle.  dmesg is not giving me any
significant errors.

I have worked at finding the problem for a few hours and have not found a lot.  But here
is what I have found:

If I reboot to kernel 4.20.16, the problem goes away.

When booted into kernel 5.0.3 dmesg gives this line:
   [   16.342693] systemd[1]: Mounting Kernel Debug File System...

but I see nothing that indicated why this might be happening.

Anyone else try kernel 5.0.3 on a Raspberry Pi?  Any thoughts on where to look for the
problem?

Thanks very much!
Will

[William Jacobs]

I have continued to to look into this and found something. 

the vchiq driver seems to behave differently under kernel 5.0.3 than it did under 4.20.16.
 Under both kernels, running the ps command shows the 4 vchiq processes.  They are:

vchiq-slot/0
vchiq-recy/0
vchiq-sync/0
vchiq-keep/0

For 4.20.16 the processes state code is S (interruptible sleep).  On 5.0.3 they are all D
(uninterruptible sleep).

Any thoughst on if these processes are what are causing the load on my Raspberry PIs to be
4.0 all the time or what to do about it would be greatly appreciated.

Thank you
Will

[Stefan Wahren]

Hi William,

>  William Jacobs <wlj15238(a)yahoo.com&gt; hat am 27. März 2019 um
> 18:33 geschrieben:
>  
>  
>  I have continued to to look into this and found something. 
>  
>  the vchiq driver seems to behave differently under kernel 5.0.3 than it did under
> 4.20.16.  Under both kernels, running the ps command shows the 4 vchiq processes.  They
> are:
>  
>  vchiq-slot/0
>  vchiq-recy/0
>  vchiq-sync/0
>  vchiq-keep/0
>  
>  For 4.20.16 the processes state code is S (interruptible sleep).  On 5.0.3 they are all D
> (uninterruptible sleep).
>  
>  Any thoughst on if these processes are what are causing the load on my Raspberry PIs to
> be 4.0 all the time or what to do about it would be greatly appreciated. 
this is a known, but more "cosmetic" issue. AFAIU this load has already been
there, but hidden:

https://github.com/raspberrypi/linux/issues/2881

> 
> Thank you
> Will