| Message ID | 20230726094027.535126-1-ming.lei@redhat.com |
|---|---|
| Headers | show |
| Series | blk-mq: fix wrong queue mapping for kdump kernel | expand |
On Wed, Jul 26, 2023 at 05:40:18PM +0800, Ming Lei wrote: > Hi, > > On arm and ppc64, 'maxcpus=1' is required for kdump kernel, > see `Documentation/admin-guide/kdump/kdump.rst`, so num_possible_cpus() > still returns all CPUs because 'maxcpus=1' just bring up one single > cpu core during booting. Just as said last time: Please drop the odd is_kdump_kernel checks in blk_mq_update_queue_map and blk_mq_alloc_tag_set instead of sprinkling this crap even further.
Hi, On arm and ppc64, 'maxcpus=1' is required for kdump kernel, see `Documentation/admin-guide/kdump/kdump.rst`, so num_possible_cpus() still returns all CPUs because 'maxcpus=1' just bring up one single cpu core during booting. blk-mq sees single queue in kdump kernel, and in driver's viewpoint there are still multiple queues, this inconsistency causes driver to apply wrong queue mapping for handling IO, and IO timeout is triggered. This issue is only triggered on managed irq in case of multiple hw queues. Some drivers takes online cpus into account for nr_hw_queues, and don't have such issue, such as nvme rdma/tcp. Meantime, single queue makes much less resource utilization, and reduce risk of kernel failure. V2: - add helper of scsi_max_nr_hw_queues() for avoiding potential build failure because scsi driver often doesn't deal with blk-mq directly - apply scsi_max_nr_hw_queues() for all scsi changes - move lpfc's change into managed irq code path Thanks, Ming Ming Lei (9): blk-mq: add blk_mq_max_nr_hw_queues() nvme-pci: use blk_mq_max_nr_hw_queues() to calculate io queues scsi: core: add helper of scsi_max_nr_hw_queues() scsi: lpfc: use blk_mq_max_nr_hw_queues() to calculate io vectors scsi: hisi: take blk_mq_max_nr_hw_queues() into account for calculating io vectors scsi: mpi3mr: take blk_mq_max_nr_hw_queues() into account for calculating io vectors scsi: megaraid: take blk_mq_max_nr_hw_queues() into account for calculating io vectors scsi: mpt3sas: take blk_mq_max_nr_hw_queues() into account for calculating io vectors scsi: pm8001: take blk_mq_max_nr_hw_queues() into account for calculating io vectors block/blk-mq.c | 16 ++++++++++++++++ drivers/nvme/host/pci.c | 2 +- drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 3 +++ drivers/scsi/lpfc/lpfc_init.c | 2 ++ drivers/scsi/megaraid/megaraid_sas_base.c | 6 +++++- drivers/scsi/mpi3mr/mpi3mr_fw.c | 3 +++ drivers/scsi/mpt3sas/mpt3sas_base.c | 4 ++-- drivers/scsi/pm8001/pm8001_init.c | 4 +++- include/linux/blk-mq.h | 1 + include/scsi/scsi_host.h | 5 +++++ 10 files changed, 41 insertions(+), 5 deletions(-)