I've been investigating, and I strongly suspect these commits for bug 1759723 are to blame.
f0aff9ccc834 genirq/affinity: assign vectors to all possible CPUs 9403a13fd07e blk-mq: simplify queue mapping & schedule with each possisble CPU As far as I can tell there are 8 other fixes we'd need to look at including, either addressing the same original commit that these patches addressed or addressing bugs related to these two patches: 16ccfff28976 nvme: pci: pass max vectors as num_possible_cpus() to pci_alloc_irq_vectors 8b834bff1b73 scsi: hpsa: fix selection of reply queue adbe552349f2 scsi: megaraid_sas: fix selection of reply queue b5b6e8c8d3b4 scsi: virtio_scsi: fix IO hang caused by automatic irq vector affinity 7bed45954b95 blk-mq: make sure hctx->next_cpu is set correctly a1c735fb7907 blk-mq: make sure that correct hctx->next_cpu is set bffa9909a6b4 blk-mq: don't keep offline CPUs mapped to hctx 0 d3056812e7df genirq/affinity: Spread irq vectors among present CPUs as far as possible Or we can revert those two patches. I'm considering both options, will provide one or two test kernels soon. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1765232 Title: Kernel 4.15.0-15 breaks Dell PowerEdge 12th Gen servers Status in linux package in Ubuntu: Confirmed Status in linux source package in Bionic: Confirmed Bug description: For Ubuntu 18.04 amd64 server, I updated the kernel from 4.15.0-13 to 4.15.0-15. The system hangs at boot up now. Rolling back to the old kernel everything works as expected. It appears to hang while trying to enumerate an SD card device, which isn't even installed. I have tried this on a Dell R620 and R820 and both have the exact same problem. I even downloaded a new installer iso from the daily builds to reinstall the OS and the installer hangs too now. Support for Dell PowerEdge 12th gen servers appears to be broken with kernel 4.15.0-15. https://imgur.com/VT9zd0w https://imgur.com/4BQPCXo To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1765232/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
