linux-kernel - Re: [PATCH 0/5] mm: rework hmm to use devm_memremap

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Date:   Wed, 23 May 2018 20:10:27 -0400
From:   Jerome Glisse <jglisse@...hat.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     akpm@...ux-foundation.org, stable@...r.kernel.org,
        Logan Gunthorpe <logang@...tatee.com>,
        Christoph Hellwig <hch@....de>, Michal Hocko <mhocko@...e.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] mm: rework hmm to use devm_memremap_pages

On Mon, May 21, 2018 at 03:35:14PM -0700, Dan Williams wrote:
> Hi Andrew, please consider this series for 4.18.
> 
> For maintainability, as ZONE_DEVICE continues to attract new users,
> it is useful to keep all users consolidated on devm_memremap_pages() as
> the interface for create "device pages".
> 
> The devm_memremap_pages() implementation was recently reworked to make
> it more generic for arbitrary users, like the proposed peer-to-peer
> PCI-E enabling. HMM pre-dated this rework and opted to duplicate
> devm_memremap_pages() as hmm_devmem_pages_create().
> 
> Rework HMM to be a consumer of devm_memremap_pages() directly and fix up
> the licensing on the exports given the deep dependencies on the mm.

I am on PTO right now so i won't be able to quickly review it all
but forcing GPL export is problematic for me now. I rather have
device driver using "sane" common helpers than creating their own
crazy thing.

Back in couple weeks i will review this some more.

> 
> Patches based on v4.17-rc6 where there are no upstream consumers of the
> HMM functionality.
> 
> ---
> 
> Dan Williams (5):
>       mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL_GPL
>       mm, devm_memremap_pages: handle errors allocating final devres action
>       mm, hmm: use devm semantics for hmm_devmem_{add,remove}
>       mm, hmm: replace hmm_devmem_pages_create() with devm_memremap_pages()
>       mm, hmm: mark hmm_devmem_{add,add_resource} EXPORT_SYMBOL_GPL
> 
> 
>  Documentation/vm/hmm.txt |    1 
>  include/linux/hmm.h      |    4 -
>  include/linux/memremap.h |    1 
>  kernel/memremap.c        |   39 +++++-
>  mm/hmm.c                 |  297 +++++++---------------------------------------
>  5 files changed, 77 insertions(+), 265 deletions(-)