blk_mq_map_queues() and multiple .map_queues() implementations expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the number of hardware queues. Hence set .nr_queues before calling these functions. This patch fixes the following kernel warning: WARNING: CPU: 0 PID: 2501 at include/linux/cpumask.h:137 Call Trace: blk_mq_run_hw_queue+0x19d/0x350 block/blk-mq.c:1508 blk_mq_run_hw_queues+0x112/0x1a0 block/blk-mq.c:1525 blk_mq_requeue_work+0x502/0x780 block/blk-mq.c:775 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Ming Lei <ming.lei@xxxxxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxxx> Cc: Johannes Thumshirn <jth@xxxxxxxxxx> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx> Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Reported-by: syzbot+d44e1b26ce5c3e77458d@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: ed76e329d74a ("blk-mq: abstract out queue map") # v5.0 Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> --- block/blk-mq.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index 7a16d61e3cd3..f174b6ad94cb 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3027,6 +3027,14 @@ static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set) static int blk_mq_update_queue_map(struct blk_mq_tag_set *set) { + /* + * blk_mq_map_queues() and multiple .map_queues() implementations + * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the + * number of hardware queues. + */ + if (set->nr_maps == 1) + set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues; + if (set->ops->map_queues && !is_kdump_kernel()) { int i;