diff --git a/block/genhd.c b/block/genhd.c                                                                                                                                                                                                     
index c26733f6324b..b56f09f5699b                                                                                                                                                                                                               
--- a/block/genhd.c                                                                                                                                                                                                                            
+++ b/block/genhd.c                                                                                                                                                                                                                            
@@ -696,6 +696,7 @@ static void __del_gendisk(struct gendisk *disk)                                                                                                                                                                            
        struct block_device *part;                                                                                                                                                                                                             
        unsigned long idx;                                                                                                                                                                                                                     
        bool start_drain;                                                                                                                                                                                                                      
+       struct blk_mq_tag_set *set = q->tag_set;                                                                                                                                                                                               
                                                                                                                                                                                                                                               
        might_sleep();                                                                                                                                                                                                                         
                                                                                                                                                                                                                                               
@@ -740,7 +741,9 @@ static void __del_gendisk(struct gendisk *disk)                                                                                                                                                                            
                bdi_unregister(disk->bdi);                                                                                                                                                                                                     
        }                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                               
+       down_read(&set->update_nr_hwq_lock);                                                                                                                                                                                                   
        blk_unregister_queue(disk);                                                                                                                                                                                                            
+       up_read(&set->update_nr_hwq_lock);                                                                                                                                                                                                     
                                                                                                                                                                                                                                               
        kobject_put(disk->part0->bd_holder_dir);                                                                                                                                                                                               
        kobject_put(disk->slave_dir);                                                                                                                                                                                                          
@@ -808,20 +811,15 @@ static void disable_elv_switch(struct request_queue *q)                                                                                                                                                                  
  */                                                                                                                                                                                                                                           
 void del_gendisk(struct gendisk *disk)                                                                                                                                                                                                        
 {                                                                                                                                                                                                                                             
-       struct blk_mq_tag_set *set;                                                                                                                                                                                                            
        unsigned int memflags;                                                                                                                                                                                                                 
                                                                                                                                                                                                                                               
        if (!queue_is_mq(disk->queue)) {                                                                                                                                                                                                       
                __del_gendisk(disk);                                                                                                                                                                                                           
        } else {                                                                                                                                                                                                                               
-               set = disk->queue->tag_set;                                                                                                                                                                                                    
-                                                                                                                                                                                                                                              
                disable_elv_switch(disk->queue);                                                                                                                                                                                               
                                                                                                                                                                                                                                               
                memflags = memalloc_noio_save();                                                                                                                                                                                               
-               down_read(&set->update_nr_hwq_lock);                                                                                                                                                                                           
                __del_gendisk(disk);                                                                                                                                                                                                           
-               up_read(&set->update_nr_hwq_lock);                                                                                                                                                                                             
                memalloc_noio_restore(memflags);                                                                                                                                                                                               
        }                                                                                                                                                                                                                                      
 }                                                                                                                                                                                                                                             
--