Hi, blk_mq_alloc_request_hctx() is used by NVMe fc/rdma/tcp/loop to connect io queue. Also the sw ctx is chosen as the 1st online cpu in hctx->cpumask. However, all cpus in hctx->cpumask may be offline. This usage model isn't well supported by blk-mq which supposes allocator is always done on one online CPU in hctx->cpumask. This assumption is related with managed irq, which also requires blk-mq to drain inflight request in this hctx when the last cpu in hctx->cpumask is going to offline. However, NVMe fc/rdma/tcp/loop don't use managed irq, so we should allow them to ask for request allocation when the specified hctx is inactive (all cpus in hctx->cpumask are offline). Fix blk_mq_alloc_request_hctx() by adding/passing flag of BLK_MQ_F_NOT_USE_MANAGED_IRQ. Ming Lei (2): blk-mq: not deactivate hctx if the device doesn't use managed irq nvme: pass BLK_MQ_F_NOT_USE_MANAGED_IRQ for fc/rdma/tcp/loop block/blk-mq.c | 6 +++++- drivers/nvme/host/fc.c | 3 ++- drivers/nvme/host/rdma.c | 3 ++- drivers/nvme/host/tcp.c | 3 ++- drivers/nvme/target/loop.c | 3 ++- include/linux/blk-mq.h | 1 + 6 files changed, 14 insertions(+), 5 deletions(-) Cc: Sagi Grimberg <sagi@xxxxxxxxxxx> Cc: Daniel Wagner <dwagner@xxxxxxx> Cc: Wen Xiong <wenxiong@xxxxxxxxxx> Cc: John Garry <john.garry@xxxxxxxxxx> -- 2.31.1
