Date:   Tue, 14 Dec 2021 18:03:52 +0100
From:   Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
To:     Tejun Heo <tj@kernel.org>
Cc:     torvalds@linuxfoundation.org, ebiederm@xmission.com,
        axboe@kernel.dk, keescook@chromium.org, oleg@redhat.com,
        peterz@infradead.org, tglx@linutronix.de, jnewsome@torproject.org,
        legion@kernel.org, luto@amacapital.net, jannh@google.com,
        linux-kernel@vger.kernel.org, security@kernel.org,
        kernel-team@fb.com, Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 2/6] cgroup: Allocate cgroup_file_ctx for
 kernfs_open_file->priv
Message-ID: <20211214170352.GA7969@blackbody.suse.cz>
References: <20211213191833.916632-1-tj@kernel.org>
 <20211213191833.916632-3-tj@kernel.org>
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On Mon, Dec 13, 2021 at 09:18:29AM -1000, Tejun Heo <tj@kernel.org> wrote:
>  static int cgroup_file_open(struct kernfs_open_file *of)

IIUC, this is common to v1 files too, i.e. cgroup_pidlist_start too.

>  static void cgroup_file_release(struct kernfs_open_file *of)
>  {
>  	struct cftype *cft = of_cft(of);
> +	struct cgroup_file_ctx *ctx = of->priv;
>  
>  	if (cft->release)
>  		cft->release(of);
> +	kfree(ctx);

Here it could free a pointer to pidlist that has different lifecycle.

Perhaps add one more slot into cgroup_file_ctx for the pidlist pointer?