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From:   Menglong Dong <menglong8.dong@gmail.com>
Date:   Wed, 26 May 2021 16:23:10 +0800
Message-ID: <CADxym3bwK3c+E7nKpogT21jMPOZEZeLa8zauxSu0VHg5AAz-Uw@mail.gmail.com>
Subject: Re: [PATCH v2 2/3] init/do_cmounts.c: introduce 'user_root' for initramfs
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     Luis Chamberlain <mcgrof@kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Kees Cook <keescook@chromium.org>,
        Sami Tolvanen <samitolvanen@google.com>, ojeda@kernel.org,
        johan@kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
        masahiroy@kernel.org, Menglong Dong <dong.menglong@zte.com.cn>,
        joe@perches.com, Jens Axboe <axboe@kernel.dk>, hare@suse.de,
        Jan Kara <jack@suse.cz>, tj@kernel.org,
        gregkh@linuxfoundation.org, song@kernel.org,
        NeilBrown <neilb@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        f.fainelli@gmail.com, arnd@arndb.de,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        wangkefeng.wang@huawei.com, Barret Rhoden <brho@google.com>,
        mhiramat@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
        vbabka@suse.cz, Alexander Potapenko <glider@google.com>,
        pmladek@suse.com, Chris Down <chris@chrisdown.name>,
        jojing64@gmail.com, terrelln@fb.com, geert@linux-m68k.org,
        mingo@kernel.org, linux-fsdevel@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>, jeyu@kernel.org
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On Wed, May 26, 2021 at 11:23 AM Eric W. Biederman
<ebiederm@xmission.com> wrote:
>
> Menglong Dong <menglong8.dong@gmail.com> writes:
>
[...]
>
> If we are going to do this something that is so small and clean it can
> be done unconditionally always.
>
> I will see if I can dig in and look at little more.  I think there is
> a reason Al Viro and H. Peter Anvin implemeted initramfs this way.
> Perhaps it was just a desire to make pivot_root unnecessary.

I don't think they are meant to make it this way. Unpack cpio to the
rootfs directly seems to be a normal operation. Maybe initramfs is just
ignored by pivot_root(), as it seems not a common scene to run the
whole system in RAM that time, I guess~

Thanks!
Menglong Dong