linux-kernel - Re: [PATCH 00/10] make "order" unsigned int

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Date:   Sun, 28 Jul 2019 01:25:02 +0800
From:   Pengfei Li <lpf.vector@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Qian Cai <cai@....pw>, Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...hsingularity.net>, vbabka@...e.cz,
        aryabinin@...tuozzo.com, osalvador@...e.de, rostedt@...dmis.org,
        mingo@...hat.com, pavel.tatashin@...rosoft.com, rppt@...ux.ibm.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 00/10] make "order" unsigned int

On Fri, Jul 26, 2019 at 3:12 PM Michal Hocko <mhocko@...nel.org> wrote:
>

Thank you for your comments.

> On Fri 26-07-19 07:48:36, Pengfei Li wrote:
> [...]
> > For the benefit, "order" may be negative, which is confusing and weird.
>
> order = -1 has a special meaning.
>

Yes. But I mean -1 can be replaced by any number greater than
MAX_ORDER - 1 and there is no reason to be negative.

> > There is no good reason not to do this since it can be avoided.
>
> "This is good because we can do it" doesn't really sound like a
> convincing argument to me. I would understand if this reduced a
> generated code, made an overall code readability much better or
> something along those lines. Also we only use MAX_ORDER range of values
> so I could argue that a smaller data type (e.g. short) should be
> sufficient for this data type.
>

I resend an email to interpret the meaning of my commit, and I would be
very grateful if you post some comments on this.

> Please note that _any_ change, alebit seemingly small, can introduce a
> subtle bug. Also each patch requires a man power to review so you have
> to understand that "just because we can" is not a strong motivation for
> people to spend their time on such a patch.

Sincerely thank you, I will keep these in mind.

> --
> Michal Hocko
> SUSE Labs

--
Pengfei