[PATCH 5.6 35/38] blk-mq: Keep set->nr_hw_queues and set->map[].nr_queues in sync

Greg Kroah-Hartman
2020-04-11T12:22:03Z

From: Bart Van Assche <bvanassche@acm.org>

commit 6e66b49392419f3fe134e1be583323ef75da1e4b upstream.

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

Fixes: ed76e329d74a ("blk-mq: abstract out queue map") # v5.0
Reported-by: syzbot+d44e1b26ce5c3e77458d@syzkaller.appspotmail.com
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Johannes Thumshirn <jth@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
block/blk-mq.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3023,6 +3023,14 @@ static int blk_mq_alloc_rq_maps(struct b

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;