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 Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1765232 Title: Kernel 4.15.0-15 breaks Dell PowerEdge 12th Gen servers To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1765232/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
