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Date:   Fri, 1 Jul 2022 21:25:51 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     David Hildenbrand <david@redhat.com>
Cc:     Felix Kuehling <felix.kuehling@amd.com>,
        Alex Sierra <alex.sierra@amd.com>, jgg@nvidia.com,
        linux-mm@kvack.org, rcampbell@nvidia.com,
        linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        hch@lst.de, jglisse@redhat.com, apopple@nvidia.com,
        willy@infradead.org
Subject: Re: [PATCH v7 01/14] mm: rename is_pinnable_pages to
 is_pinnable_longterm_pages
Message-Id: <20220701212551.7198162dbd65746a69bc41b4@linux-foundation.org>
In-Reply-To: <49315889-96de-8e41-f8ee-dd5b33c5e1db@redhat.com>
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        <f00f9c93-c115-d222-dc8c-11493ccd2567@redhat.com>
        <575b48a6-e372-acda-9a7c-449f307a588c@amd.com>
        <49315889-96de-8e41-f8ee-dd5b33c5e1db@redhat.com>
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On Thu, 30 Jun 2022 00:15:06 +0200 David Hildenbrand <david@redhat.com> wrote:

> On 30.06.22 00:08, Felix Kuehling wrote:
> > On 2022-06-29 03:33, David Hildenbrand wrote:
> >> On 29.06.22 05:54, Alex Sierra wrote:
> >>> is_pinnable_page() and folio_is_pinnable() were renamed to
> >>> is_longterm_pinnable_page() and folio_is_longterm_pinnable()
> >>> respectively. These functions are used in the FOLL_LONGTERM flag
> >>> context.
> >> Subject talks about "*_pages"
> >>
> >>
> >> Can you elaborate why the move from mm.h to memremap.h is justified?
> > 
> > Patch 2 adds is_device_coherent_page in memremap.h and updates 
> > is_longterm_pinnable_page to call is_device_coherent_page. memremap.h 
> > cannot include mm.h because it is itself included by mm.h. So the choice 
> > was to move is_longterm_pinnable_page to memremap.h, or move 
> > is_device_coherent_page and all its dependencies to mm.h. The latter 
> > would have been a bigger change.
> 
> I really don't think something mm generic that compiles without
> ZONE_DEVICE belongs into memremap.h. Please find a cleaner way to get
> this done.

(without having bothered to look at the code...)

The solution is always to create a new purpose-specific header file.