Re: [PATCH v3 2/8] blk-mq: Keep set->nr_hw_queues and set->map[].nr_queues in sync

[Ming Lei <ming.lei@redhat.com>]

On Tue, Feb 25, 2020 at 08:47:27AM +0800, Ming Lei wrote:
> On Thu, Feb 20, 2020 at 07:22:37PM -0800, Bart Van Assche wrote:
> > 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@infradead.org>
> > Cc: Ming Lei <ming.lei@redhat.com>
> > Cc: Hannes Reinecke <hare@suse.com>
> > Cc: Johannes Thumshirn <jth@kernel.org>
> > Reported-by: syzbot+d44e1b26ce5c3e77458d@syzkaller.appspotmail.com
> > Fixes: ed76e329d74a ("blk-mq: abstract out queue map") # v5.0
> > Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> > ---
> >  block/blk-mq.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/block/blk-mq.c b/block/blk-mq.c
> > index f298500e6dda..a92444c077bc 100644
> > --- a/block/blk-mq.c
> > +++ b/block/blk-mq.c
> > @@ -3023,6 +3023,14 @@ 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;
> >  
> > 
> 
> Reviewed-by: Ming Lei <ming.lei@redhat.com>
> 

Hi Jens,

This one and the 3rd patch may belong to 5.6, any chance to consider
them to 5.6?


Thanks,
Ming