power8 kernel panic

[Newell Jensen]

I ran into this bug while trying to deploy a power8 (powerVM) LPAR via MAAS. I was using Trusty with hwe-v kernel. Most of the time, using the same images, I never have issues but I have seen this panic happen randomly.

Here is the output from the console during deployment:

http://paste.ubuntu.com/15117191/

This should have the information that is needed.

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1547192

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Leann Ogasawara (leannogasawara)]

[ 12.893105] VFS: Cannot open root device "disk/by-path/ip-172.24.25.1:3260-iscsi-iqn.2004-05.com.ubu" or unknown-block(0,0): error -6
[ 12.893109] Please append a correct "root=" boot option; here are the available partitions:

Are you sure this is pointing to a valid location?

[Newell Jensen (newell-jensen)]

I believe so as this kernel panic does not happen 9 times out of 10. I am currently testing whether adding root_delay=30 will help.

[Newell Jensen (newell-jensen)]

FWIW, I have not seen the kernel panic since setting the kernel parameter rootdelay=30. However, as it was intermittent to begin with, not sure if it will creep up again at some point.

[Christian Reis (kiko)]

We have just encountered this issue on a large deployment on one random node, but it's not a Power8 machines -- just a regular HP DL360. Here's an excerpt from the log:

[ 15.623526] tty ttyS9: hash matches
[ 15.625028] rtc_cmos 00:00: setting system clock to 2017-06-07 00:45:20 UTC (1496796320)
[ 15.627839] BIOS EDD facility v0.16 2004-Jun-25, 0 devices found
[ 15.629838] EDD information not available.
[ 15.631363] md: Waiting for all devices to be available before autodetect
[ 15.661880] md: If you don't use raid, use raid=noautodetect
[ 15.687911] md: Autodetecting RAID arrays.
[ 15.706358] md: Scanned 0 and added 0 devices.
[ 15.726206] md: autorun ...
[ 15.738696] md: ... autorun DONE.
[ 15.753535] VFS: Cannot open root device "disk/by-path/ip-10.144.10.62:3260-iscsi-iqn.2004-05.com.ub" or unknown-block(0,0): error -6
[ 15.807400] Please append a correct "root=" boot option; here are the available partitions:
[ 15.845000] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

I bet this is not actually a Power problem, but instead something which causes the iscsi mount to fail.