Merge tag 'md-6.14-20250124' of https://git.kernel.org/pub/scm/linux/kernel/git/mdraid/linux into block-6.14

Pull MD fix from Song:

"Fix a md-cluster regression introduced in the 6.12 release."

* tag 'md-6.14-20250124' of https://git.kernel.org/pub/scm/linux/kernel/git/mdraid/linux:
  md/md-bitmap: Synchronize bitmap_get_stats() with bitmap lifetime

Author: axboe

drivers/md/md-bitmap.c

@@ -2355,7 +2355,10 @@ static int bitmap_get_stats(void *data, struct md_bitmap_stats *stats)
 
 	if (!bitmap)
 		return -ENOENT;
-
+	if (bitmap->mddev->bitmap_info.external)
+		return -ENOENT;
+	if (!bitmap->storage.sb_page) /* no superblock */
+		return -EINVAL;
 	sb = kmap_local_page(bitmap->storage.sb_page);
 	stats->sync_size = le64_to_cpu(sb->sync_size);
 	kunmap_local(sb);

drivers/md/md.c

@@ -8376,6 +8376,10 @@ static int md_seq_show(struct seq_file *seq, void *v)
 		return 0;
 
 	spin_unlock(&all_mddevs_lock);
+
+	/* prevent bitmap to be freed after checking */
+	mutex_lock(&mddev->bitmap_info.mutex);
+
 	spin_lock(&mddev->lock);
 	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
 		seq_printf(seq, "%s : ", mdname(mddev));
@@ -8451,6 +8455,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
 		seq_printf(seq, "\n");
 	}
 	spin_unlock(&mddev->lock);
+	mutex_unlock(&mddev->bitmap_info.mutex);
 	spin_lock(&all_mddevs_lock);
 
 	if (mddev == list_last_entry(&all_mddevs, struct mddev, all_mddevs))