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Subject: Re: [PATCH] mm: remove some useless comments of node_stat_item
To:     Matthew Wilcox <willy@infradead.org>
CC:     <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
References: <20230713114915.74671-1-linmiaohe@huawei.com>
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 <55c255df-9c7c-744f-e1a1-27602fcb5509@huawei.com>
 <ZK/uukqNMQYyyNif@casper.infradead.org>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <d9efcca5-0448-2d0d-84e0-9af99f0c0701@huawei.com>
Date:   Fri, 14 Jul 2023 09:36:15 +0800
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On 2023/7/13 20:31, Matthew Wilcox wrote:
> On Thu, Jul 13, 2023 at 08:18:29PM +0800, Miaohe Lin wrote:
>> On 2023/7/13 20:10, Matthew Wilcox wrote:
>>> On Thu, Jul 13, 2023 at 07:49:15PM +0800, Miaohe Lin wrote:
>>>> Some comments of node_stat_item are not that helpful and even confusing,
>>>> so remove them. No functional change intended.
>>>
>>> No, that's very useful and important.  Why does it confuse you?
>>
>> Thanks for your quick respond.
>>
>> I just can't figure out what these comments want to tell. Could you help explain these?
> 
> Don't snip the thing you want explained to you!
> 
>         NR_INACTIVE_ANON = NR_LRU_BASE, /* must match order of LRU_[IN]ACTIVE */
> -       NR_ACTIVE_ANON,         /*  "     "     "   "       "         */
> -       NR_INACTIVE_FILE,       /*  "     "     "   "       "         */
> -       NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
> -       NR_UNEVICTABLE,         /*  "     "     "   "       "         */
> +	NR_ACTIVE_ANON,
> +       NR_INACTIVE_FILE,
> +       NR_ACTIVE_FILE,
> +	NR_UNEVICTABLE,
> 
> What this is communicating to me is that these five items
> (NR_INACTIVE_ANON to NR_UNEVICTABLE) must stay in the same order with
> LRU_INACTIVE and LRU_ACTIVE.  By removing the ditto-marks from the
> subsequent four lines, you've made the comment say that this one line
> must stay in the same order as LRU_INACTIVE and LRU_ACTIVE ... which
> makes no sense at all.

I see. Many thanks for your kind explanation. :)