linux-kernel - Re: [PATCH v4 1/1] docs/mm: Physical Memory: add structure, introduction and nodes description

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Message-ID: <AC10188D-6728-478F-A95D-1A460958533A@suse.cz>
Date:   Tue, 24 Jan 2023 14:40:54 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Mike Rapoport <rppt@...nel.org>
CC:     Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Bagas Sanjaya <bagasdotme@...il.com>,
        David Hildenbrand <david@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...nel.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH v4 1/1] docs/mm: Physical Memory: add structure, introduction and nodes description



On January 24, 2023 12:16:20 PM GMT+01:00, Mike Rapoport <rppt@...nel.org> wrote:
>On Tue, Jan 24, 2023 at 12:00:07PM +0100, Vlastimil Babka wrote:
>> On 1/15/23 19:42, Mike Rapoport wrote:
>> > From: "Mike Rapoport (IBM)" <rppt@...nel.org>
>> > 
>> > Add structure, introduction and Nodes section to Physical Memory
>> > chapter.
>> > 
>> > As the new documentation references core-api/dma-api and mm/page_reclaim,
>> > add page labels to those documents.
>> > 
>> > Reviewed-by: Bagas Sanjaya <bagasdotme@...il.com>
>> > Reviewed-by: Lorenzo Stoakes <lstoakes@...il.com>
>> > Acked-by: Michal Hocko <mhocko@...e.com>
>> > Signed-off-by: Mike Rapoport (IBM) <rppt@...nel.org>
>> 
>> Acked-by: Vlastimil Babka <vbabka@...e.cz>
>> 
>> A small bug to fix below?
>> 
>> <snip>
>> 
>> > +
>> > +Along with the node structures, kernel maintains an array of ``nodemask_t``
>> > +bitmasks called ``node_states``. Each bitmask in this array represents a set of
>> > +nodes with particular properties as defined by ``enum node_states``:
>> > +
>> > +``N_POSSIBLE``
>> > +  The node could become online at some point.
>> > +``N_ONLINE``
>> > +  The node is online.
>> > +``N_NORMAL_MEMORY``
>> > +  The node has regular memory.
>> > +``N_HIGH_MEMORY``
>> > +  The node has regular or high memory. When ``CONFIG_HIGHMEM`` is disabled
>> > +  aliased to ``N_NORMAL_MEMORY``.
>> 
>> Noted.
>> 
>> > +``N_MEMORY``
>> > +  The node has memory(regular, high, movable)
>> > +``N_CPU``
>> > +  The node has one or more CPUs
>> > +
>> > +For each node that has a property described above, the bit corresponding to the
>> > +node ID in the ``node_states[<property>]`` bitmask is set.
>> > +
>> > +For example, for node 2 with normal memory and CPUs, bit 2 will be set in ::
>> > +
>> > +  node_states[N_POSSIBLE]
>> > +  node_states[N_ONLINE]
>> > +  node_states[N_NORMAL_MEMORY]
>> > +  node_states[N_MEMORY]
>> > +  node_states[N_CPU]
>> 
>> Should it be set also in node_states[N_HIGH_MEMORY]?
> 
>You mean because of the aliasing of N_NORMAL_MEMORY and N_HIGH_MEMORY?

No I meant due to "The node has regular or high memory." Or do I misunderstand?