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Subject: Re: [PATCH] mm/vmscan: DRY cleanup for do_try_to_free_pages()
To:     Chris Down <chris@chrisdown.name>
Cc:     Michal Hocko <mhocko@suse.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, akpm@linux-foundation.org
References: <20201218102217.186836-1-jian.w.wen@oracle.com>
 <20201218105153.GX32193@dhcp22.suse.cz>
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 <20201218142717.GA32193@dhcp22.suse.cz>
 <63e8a821-a3f6-47a6-f438-b27c32f4a05f@oracle.com>
 <X91Vg1Mg1nPk/Bsx@chrisdown.name>
From:   Jacob Wen <jian.w.wen@oracle.com>
Message-ID: <fc257fe6-f2e4-bc53-1943-533661378fc5@oracle.com>
Date:   Sat, 19 Dec 2020 11:18:43 +0800
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On 12/19/20 9:21 AM, Chris Down wrote:
> Jacob Wen writes:
>> set_task_reclaim_state() is a function with 3 lines of code of which 
>> 2 lines contain WARN_ON_ONCE.
>>
>> I am not comfortable with the current repetition.
>
> Ok, but could you please go into _why_ others should feel that way 
> too? There are equally also reasons to err on the side of leaving code 
> as-is -- since we know it already works, and this code generally has 
> pretty high inertia -- and avoid mutation of code without concrete 
> description of the benefits.

I don't get your point. The patch doesn't change code of 
set_task_reclaim_state(), so I am fine with the repeated WARN_ON_ONCE.

I mean I prefer removing duplicate code to avoid going down the rabbit 
hole of set_task_reclaim_state().

It's a fundamental principle to me to move the code into its own 
function. I'd like to hear the others' opinions.