diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 845c5d7af9091877d87566764277ff9a40e44ca0..bffadbb67e4753edbe10a5b67e58af9afb1da521 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1876,8 +1876,10 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
 		bu_init(c);
 	else {
 		dbg_gen("disable bulk-read");
+		mutex_lock(&c->bu_mutex);
 		kfree(c->bu.buf);
 		c->bu.buf = NULL;
+		mutex_unlock(&c->bu_mutex);
 	}
 
 	ubifs_assert(c->lst.taken_empty_lebs > 0);