Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 13 Jul 2023 13:31:54 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: remove some useless comments of node_stat_item
Message-ID: <ZK/uukqNMQYyyNif@casper.infradead.org>
References: <20230713114915.74671-1-linmiaohe@huawei.com>
 <ZK/ppvBO00rbspa8@casper.infradead.org>
 <55c255df-9c7c-744f-e1a1-27602fcb5509@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <55c255df-9c7c-744f-e1a1-27602fcb5509@huawei.com>
Precedence: bulk

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.