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Date:   Sat, 19 Feb 2022 05:53:37 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Rik van Riel <riel@surriel.com>
Cc:     linux-kernel@vger.kernel.org, kernel-team@fb.com,
        linux-fsdevel@vger.kernel.org, paulmck@kernel.org,
        gscrivan@redhat.com, Eric Biederman <ebiederm@xmission.com>,
        Chris Mason <clm@fb.com>
Subject: Re: [PATCH 1/2] vfs: free vfsmount through rcu work from kern_unmount
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References: <20220218183114.2867528-1-riel@surriel.com>
 <20220218183114.2867528-2-riel@surriel.com>
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On Fri, Feb 18, 2022 at 01:31:13PM -0500, Rik van Riel wrote:

>  struct super_block;
>  struct vfsmount;
> @@ -73,6 +74,7 @@ struct vfsmount {
>  	struct super_block *mnt_sb;	/* pointer to superblock */
>  	int mnt_flags;
>  	struct user_namespace *mnt_userns;
> +	struct rcu_work free_rwork;
>  } __randomize_layout;

Wait, what?  First of all, that has no business being in vfsmount -
everything that deeply internal belongs in struct mount, not in
its public part.  Moreover, there's already mount->mnt_rcu, so what's
the point duplicating that?