diff --git a/block/blk-mq.c b/block/blk-mq.c
index e68b71b85a7eaf0e3097debe8bf4dc4078e7a038..594eea04266e6d05f7256255552a1c4c72c664f3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1600,6 +1600,7 @@ static int blk_mq_hctx_notify(void *data, unsigned long action,
 	return NOTIFY_OK;
 }
 
+/* hctx->ctxs will be freed in queue's release handler */
 static void blk_mq_exit_hctx(struct request_queue *q,
 		struct blk_mq_tag_set *set,
 		struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
@@ -1618,7 +1619,6 @@ static void blk_mq_exit_hctx(struct request_queue *q,
 
 	blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
 	blk_free_flush_queue(hctx->fq);
-	kfree(hctx->ctxs);
 	blk_mq_free_bitmap(&hctx->ctx_map);
 }
 
@@ -1891,8 +1891,12 @@ void blk_mq_release(struct request_queue *q)
 	unsigned int i;
 
 	/* hctx kobj stays in hctx */
-	queue_for_each_hw_ctx(q, hctx, i)
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (!hctx)
+			continue;
+		kfree(hctx->ctxs);
 		kfree(hctx);
+	}
 
 	kfree(q->queue_hw_ctx);
 
diff --git a/block/genhd.c b/block/genhd.c
index 666e11b8398378d145552b18e51c190c18847a9f..ea982eadaf6380b974d6b1d39a7197085217ac91 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -422,9 +422,9 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
 	/* allocate ext devt */
 	idr_preload(GFP_KERNEL);
 
-	spin_lock(&ext_devt_lock);
+	spin_lock_bh(&ext_devt_lock);
 	idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);
-	spin_unlock(&ext_devt_lock);
+	spin_unlock_bh(&ext_devt_lock);
 
 	idr_preload_end();
 	if (idx < 0)
@@ -449,9 +449,9 @@ void blk_free_devt(dev_t devt)
 		return;
 
 	if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
-		spin_lock(&ext_devt_lock);
+		spin_lock_bh(&ext_devt_lock);
 		idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
-		spin_unlock(&ext_devt_lock);
+		spin_unlock_bh(&ext_devt_lock);
 	}
 }
 
@@ -690,13 +690,13 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
 	} else {
 		struct hd_struct *part;
 
-		spin_lock(&ext_devt_lock);
+		spin_lock_bh(&ext_devt_lock);
 		part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
 		if (part && get_disk(part_to_disk(part))) {
 			*partno = part->partno;
 			disk = part_to_disk(part);
 		}
-		spin_unlock(&ext_devt_lock);
+		spin_unlock_bh(&ext_devt_lock);
 	}
 
 	return disk;
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index eb1fed5bd516ffac33c850eed47fad402250c686..3ccef9eba6f9dc53cecb785c23582cbdeb3b8618 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -406,6 +406,7 @@ config BLK_DEV_RAM_DAX
 
 config BLK_DEV_PMEM
 	tristate "Persistent memory block device support"
+	depends on HAS_IOMEM
 	help
 	  Saying Y here will allow you to use a contiguous range of reserved
 	  memory as one or more persistent block devices.