linux-kernel - Re: [PATCH] binderfs: rework superblock destruction

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Message-ID: <20220817140149.pfakskeyxkqcot54@wittgenstein>
Date:   Wed, 17 Aug 2022 16:01:49 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dongliang Mu <mudongliangabcd@...il.com>,
        Dongliang Mu <dzm91@...t.edu.cn>,
        Arve Hjønnevåg <arve@...roid.com>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Carlos Llamas <cmllamas@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        syzkaller <syzkaller@...glegroups.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] binderfs: rework superblock destruction

On Wed, Aug 17, 2022 at 02:59:02PM +0100, Al Viro wrote:
> On Wed, Aug 17, 2022 at 03:03:06PM +0200, Christian Brauner wrote:
> 
> > +static void binderfs_kill_super(struct super_block *sb)
> > +{
> > +	struct binderfs_info *info = sb->s_fs_info;
> > +
> > +	if (info && info->ipc_ns)
> > +		put_ipc_ns(info->ipc_ns);
> > +
> > +	kfree(info);
> > +	kill_litter_super(sb);
> > +}
> 
> Other way round, please - shut the superblock down, *then*
> free the objects it'd been using.  IOW,

I wondered about that but a lot of places do it the other way around.
So maybe the expected order should be documented somewhere.