Probably the  best thing to do is:

diff --git a/drivers/md/md.c b/drivers/md/md.c
index d059af5..b19a1c8 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -5629,10 +5629,7 @@ static int get_bitmap_file(struct mddev * mddev, void __user * arg)
 	char *ptr, *buf = NULL;
 	int err = -ENOMEM;
 
-	if (md_allow_write(mddev))
-		file = kmalloc(sizeof(*file), GFP_NOIO);
-	else
-		file = kmalloc(sizeof(*file), GFP_KERNEL);
+	file = kmalloc(sizeof(*file), GFP_NOIO);
 
 	if (!file)
 		goto out;

A failure here is not likely and not catastrophic.

Does it fix the situation for you?