no need to protect against put_user_ns(NULL)

it's a no-op
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

arch/x86/kernel/cpu/resctrl/rdtgroup.c

@@ -2108,8 +2108,7 @@ static int rdt_init_fs_context(struct fs_context *fc)
 	ctx->kfc.magic = RDTGROUP_SUPER_MAGIC;
 	fc->fs_private = &ctx->kfc;
 	fc->ops = &rdt_fs_context_ops;
-	if (fc->user_ns)
-		put_user_ns(fc->user_ns);
+	put_user_ns(fc->user_ns);
 	fc->user_ns = get_user_ns(&init_user_ns);
 	fc->global = true;
 	return 0;

fs/sysfs/mount.c

@@ -72,8 +72,7 @@ static int sysfs_init_fs_context(struct fs_context *fc)
 	fc->fs_private = kfc;
 	fc->ops = &sysfs_fs_context_ops;
 	if (netns) {
-		if (fc->user_ns)
-			put_user_ns(fc->user_ns);
+		put_user_ns(fc->user_ns);
 		fc->user_ns = get_user_ns(netns->user_ns);
 	}
 	fc->global = true;

kernel/cgroup/cgroup.c

@@ -2184,8 +2184,7 @@ static int cgroup_init_fs_context(struct fs_context *fc)
 		fc->ops = &cgroup_fs_context_ops;
 	else
 		fc->ops = &cgroup1_fs_context_ops;
-	if (fc->user_ns)
-		put_user_ns(fc->user_ns);
+	put_user_ns(fc->user_ns);
 	fc->user_ns = get_user_ns(ctx->ns->user_ns);
 	fc->global = true;
 	return 0;