Re: [PATCH v2] proc: "mount -o lookup=" support

[Alexey Dobriyan]

On Wed, Jan 19, 2022 at 06:48:03PM +0300, Alexey Dobriyan wrote:
> 	# mount -t proc -o lookup=/ proc /proc

> +static int proc_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
> +{
> +	struct proc_fs_context *src = fc->fs_private;
> +	struct proc_fs_context *dst;
> +
> +	dst = kmemdup(src, sizeof(struct proc_fs_context), GFP_KERNEL);
> +	if (!dst) {
> +		return -ENOMEM;
> +	}
> +
> +	dst->lookup_list = kmemdup(dst->lookup_list, dst->lookup_list_len, GFP_KERNEL);
> +	if (!dst->lookup_list) {
> +		kfree(dst);
> +		return -ENOMEM;
> +	}
> +	get_pid_ns(dst->pid_ns);
> +
> +	fc->fs_private = dst;
> +	return 0;
> +}

Stephen, sorry for not replying earlier.

I don't pretend to understand fully what ->dup() is supposed to do.
And the above code was not tested.

In particular

	p->a = kmemdup(p->a, ...)

reads like "MEMORY LEAK" on the first glance but it is not.

Understanding ->dup is the next thing.