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From:   "Eric W. Biederman" <ebiederm@xmission.com>
To:     Huacai Chen <chenhuacai@loongson.cn>
Cc:     Luis Chamberlain <mcgrof@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>, chenhuacai@kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <20230509104127.1997562-1-chenhuacai@loongson.cn>
Date:   Wed, 10 May 2023 10:44:43 -0500
In-Reply-To: <20230509104127.1997562-1-chenhuacai@loongson.cn> (Huacai Chen's
        message of "Tue, 9 May 2023 18:41:27 +0800")
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Subject: Re: [PATCH RFC] kthread: Unify kernel_thread() and user_mode_thread()
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Huacai Chen <chenhuacai@loongson.cn> writes:

> Commit 343f4c49f2438d8 ("kthread: Don't allocate kthread_struct for init
> and umh") introduces a new function user_mode_thread() for init and umh.
> But the name is a bit confusing because init and umh are indeed kernel
> threads at creation time, the real difference is "they will become user
> processes".

No they are not "kernel threads" at creation time.  At creation time
init and umh are threads running in the kernel.

It is a very important distinction and you are loosing it.

Because they don't have a kthread_struct such tasks in the kernel
are not allowed to depend on anything that is ``kthread''.

Having this a separate function highlights the distinction.
Highlighting should hopefully cause people to ask why there is a
distinction, and what is going on.

> So let's unify the kernel_thread() and user_mode_thread() to
> kernel_thread() again, and add a new 'user' parameter for init and
> umh

Now that is confusing.

Eric