md: don't destroy serial_info_pool if serialize_policy is true

The serial_info_pool is needed if array sets serialize_policy to
true, so don't destroy it.
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Song Liu <songliubraving@fb.com>

drivers/md/md-bitmap.c

@@ -1789,8 +1789,10 @@ void md_bitmap_destroy(struct mddev *mddev)
 		return;
 
 	md_bitmap_wait_behind_writes(mddev);
-	mempool_destroy(mddev->serial_info_pool);
-	mddev->serial_info_pool = NULL;
+	if (!mddev->serialize_policy) {
+		mempool_destroy(mddev->serial_info_pool);
+		mddev->serial_info_pool = NULL;
+	}
 
 	mutex_lock(&mddev->bitmap_info.mutex);
 	spin_lock(&mddev->lock);
@@ -2476,8 +2478,10 @@ backlog_store(struct mddev *mddev, const char *buf, size_t len)
 	mddev->bitmap_info.max_write_behind = backlog;
 	if (!backlog && mddev->serial_info_pool) {
 		/* serial_info_pool is not needed if backlog is zero */
-		mempool_destroy(mddev->serial_info_pool);
-		mddev->serial_info_pool = NULL;
+		if (!mddev->serialize_policy) {
+			mempool_destroy(mddev->serial_info_pool);
+			mddev->serial_info_pool = NULL;
+		}
 	} else if (backlog && !mddev->serial_info_pool) {
 		/* serial_info_pool is needed since backlog is not zero */
 		struct md_rdev *rdev;