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From: Michal Hocko <mhocko@kernel.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Christoph Hellwig" <hch@lst.de>, "Linux MM" <linux-mm@kvack.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 1/7] mm, devm_memremap_pages: Mark devm_memremap_pages() EXPORT_SYMBOL_GPL
Date: Tue, 23 Oct 2018 19:01:36 +0200	[thread overview]
Message-ID: <20181023170136.GV18839@dhcp22.suse.cz> (raw)
In-Reply-To: <CAPcyv4hMFQYekvZWMzKYckuVLSGd3GizRtoDudFBQj5bfxD3Mw@mail.gmail.com>

On Wed 17-10-18 09:30:58, Dan Williams wrote:
> On Wed, Oct 17, 2018 at 1:18 AM Michal Hocko <mhocko@kernel.org> wrote:
[...]
> > > Again, devm_memremap_pagex() exposes and relies upon core kernel
> > > internal assumptions and will continue to evolve along with 'struct
> > > page', memory hotplug, and support for new memory types / topologies.
> > > Only an in-kernel GPL-only driver is expected to keep up with this
> > > ongoing evolution. This interface, and functionality derived from this
> > > interface, is not suitable for kernel-external drivers.
> >
> > I do not follow this line of argumentation though. We generally do not
> > care about out-of-tree modules and breaking them if the interface has to
> > be updated.
> 
> Exactly right. The EXPORT_SYMBOL_GPL is there to say that this api has
> deep enough ties into the core kernel to lower the confidence that the
> API will stay stable from one kernel revision to the next. It's also
> an api that is attracting widening and varied reuse and the long term
> health of the implementation depends on being able to peer deeply into
> its users and refactor the interface and the core kernel as a result.

I am sorry I do not follow. For in-tree modules you have to update users
whether the export is GPL or not and we do not care _at all_ about out
of tree because we do not guarantee _any_ kABI/API stability
(Documentation/process/stable-api-nonsense.rst).

Anyway, I do not really care much, but I find the way of the
argumentation dubious. I can clearly understand a simple line "me as the
author want this GPL - live with that".
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-10-23 17:01 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-12 17:49 [PATCH v7 0/7] mm: Merge hmm into devm_memremap_pages, mark GPL-only Dan Williams
2018-10-12 17:49 ` [PATCH v7 1/7] mm, devm_memremap_pages: Mark devm_memremap_pages() EXPORT_SYMBOL_GPL Dan Williams
2018-10-17  8:17   ` Michal Hocko
2018-10-17 16:30     ` Dan Williams
2018-10-23 17:01       ` Michal Hocko [this message]
2018-10-12 17:49 ` [PATCH v7 2/7] mm, devm_memremap_pages: Kill mapping "System RAM" support Dan Williams
2018-10-12 17:49 ` [PATCH v7 3/7] mm, devm_memremap_pages: Fix shutdown handling Dan Williams
2018-10-12 17:49 ` [PATCH v7 4/7] mm, devm_memremap_pages: Add MEMORY_DEVICE_PRIVATE support Dan Williams
2018-10-12 17:49 ` [PATCH v7 5/7] mm, hmm: Use devm semantics for hmm_devmem_{add, remove} Dan Williams
2018-10-12 17:50 ` [PATCH v7 6/7] mm, hmm: Replace hmm_devmem_pages_create() with devm_memremap_pages() Dan Williams
2018-10-12 17:50 ` [PATCH v7 7/7] mm, hmm: Mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL Dan Williams
2018-10-12 18:14 ` [PATCH v7 0/7] mm: Merge hmm into devm_memremap_pages, mark GPL-only Jerome Glisse
  -- strict thread matches above, loose matches on Subject: below --
2018-10-12 17:47 Dan Williams
2018-10-12 17:47 ` [PATCH v7 1/7] mm, devm_memremap_pages: Mark devm_memremap_pages() EXPORT_SYMBOL_GPL Dan Williams

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