Ubuntu
linux package

  1. Bionic (18.04)
  2. Bug #1790480
  3. Comment #2

Comment 2 for bug 1790480

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2018-09-05 05:06 EDT-------
(In reply to comment #8)
> @IBM: Even if we do not have NVMe devices in our Z machine (hence we cannot
> test this on s390x by ourselves) it would be good and helpful if you can
> share a description / or some steps of a potential test case.
> This would help judging the regression risk in case of an SRU to 18.04 (and
> is needed for a SRU anyway).

The trigger is a PCI function whose driver requests more interrupts than the architectural maximum. Currently this is only possible with a machine that supports 64 CPUs (or more) with a NVMe function attached. Note that the LPAR does not have to use >=64 CPUs since the NVMe driver uses num_possible_cpus() which is resolved to the machine maximum on s390 (since all CPUs are hot-pluggable). The oops happens after the driver calls pci_alloc_irq_vectors during device probing - so most likely the system will panic during boot.