From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-fsdevel-owner@vger.kernel.org>
Received: from zeniv.linux.org.uk ([195.92.253.2]:40288 "EHLO
        ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752695AbdKWOrl (ORCPT
        <rfc822;linux-fsdevel@vger.kernel.org>);
        Thu, 23 Nov 2017 09:47:41 -0500
Date: Thu, 23 Nov 2017 14:47:35 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Michal Hocko <mhocko@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] fs: handle shrinker registration failure in sget_userns
Message-ID: <20171123144735.GA21978@ZenIV.linux.org.uk>
References: <20171123115247.30685-1-mhocko@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20171123115247.30685-1-mhocko@kernel.org>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On Thu, Nov 23, 2017 at 12:52:47PM +0100, Michal Hocko wrote:
> @@ -503,12 +504,18 @@ struct super_block *sget_userns(struct file_system_type *type,
>  		s = alloc_super(type, (flags & ~SB_SUBMOUNT), user_ns);
>  		if (!s)
>  			return ERR_PTR(-ENOMEM);
> +		if (register_shrinker(&s->s_shrink)) {
> +			spin_unlock(&sb_lock);
> +			destroy_unused_super(s);
> +			return ERR_PTR(-ENOMEM);

Have you even tested that?  What the hell is that spin_unlock() doing there?