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Date:   Fri, 1 May 2020 05:34:29 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Joonsoo Kim <js1304@gmail.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Laura Abbott <labbott@redhat.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Michal Hocko <mhocko@suse.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Roman Gushchin <guro@fb.com>, Minchan Kim <minchan@kernel.org>,
        Rik van Riel <riel@surriel.com>,
        Christian Koenig <christian.koenig@amd.com>,
        Huang Rui <ray.huang@amd.com>,
        Eric Biederman <ebiederm@xmission.com>,
        "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Pavel Machek <pavel@ucw.cz>, kernel-team@lge.com,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2 00/10] change the implementation of the PageHighMem()
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On Fri, May 01, 2020 at 09:15:30PM +0900, Joonsoo Kim wrote:
> I think that PageHighMemZone() is long and complicated enough to have
> a macro.

It is.  But then again it also shouldn't really be used by anything
but MM internals.

> 
> PageHighMemZone(page) = is_highmem_idx(zone_idx(page_zone(page))
> 
> Instead of open-code, how about changing the style of macro like as
> page_from_highmem()? What PageHighMemZone() represent is derivated
> attribute from the page so PageXXX() style may not be appropriate.

Maybe page_is_highmem_zone() with a big kerneldoc comment explaining
the use case?  Bonus points of killing enough users that it can be
in mm/internal.h.