From: Jerome Glisse <jglisse@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: akpm@linux-foundation.org, stable@vger.kernel.org,
Balbir Singh <bsingharora@gmail.com>,
Logan Gunthorpe <logang@deltatee.com>,
Christoph Hellwig <hch@lst.de>, Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 0/7] mm: Merge hmm into devm_memremap_pages, mark GPL-only
Date: Fri, 12 Oct 2018 14:14:25 -0400 [thread overview]
Message-ID: <20181012181425.GF6593@redhat.com> (raw)
In-Reply-To: <153936657159.1198040.4489957977352276272.stgit@dwillia2-desk3.amr.corp.intel.com>
On Fri, Oct 12, 2018 at 10:49:31AM -0700, Dan Williams wrote:
> [ apologies for the resend, script error ]
>
> Changes since v6 [1]:
> * Rebase on next-20181008 and fixup conflicts with the xarray conversion
> and hotplug optimizations
> * It has soaked on a 0day visible branch for a few days without any
> reports.
>
> [1]: https://lkml.org/lkml/2018/9/13/104
>
> ---
>
> Hi Andrew,
>
> Jérôme has reviewed the cleanups, thanks Jérôme. We still disagree on
> the EXPORT_SYMBOL_GPL status of the core HMM implementation, but Logan,
> Christoph and I continue to support marking all devm_memremap_pages()
> derivatives EXPORT_SYMBOL_GPL.
>
> HMM has been upstream for over a year, with no in-tree users it is clear
> it was designed first and foremost for out of tree drivers. It takes
> advantage of a facility Christoph and I spearheaded to support
> persistent memory. It continues to see expanding use cases with no clear
> end date when it will stop attracting features / revisions. It is not
> suitable to export devm_memremap_pages() as a stable 3rd party driver
> api.
>
> devm_memremap_pages() is a facility that can create struct page entries
> for any arbitrary range and give out-of-tree drivers the ability to
> subvert core aspects of page management. It, and anything derived from
> it (e.g. hmm, pcip2p, etc...), is a deep integration point into the core
> kernel, and an EXPORT_SYMBOL_GPL() interface.
>
> Commit 31c5bda3a656 "mm: fix exports that inadvertently make put_page()
> EXPORT_SYMBOL_GPL" was merged ahead of this series to relieve some of
> the pressure from innocent consumers of put_page(), but now we need this
> series to address *producers* of device pages.
>
> More details and justification in the changelogs. The 0day
> infrastructure has reported success across 152 configs and this survives
> the libnvdimm unit test suite. Aside from the controversial bits the
> diffstat is compelling at:
>
> 7 files changed, 126 insertions(+), 323 deletions(-)
>
> Note that the series has some minor collisions with Alex's recent series
> to improve devm_memremap_pages() scalability [2]. So, whichever you take
> first the other will need a minor rebase.
>
> [2]: https://www.lkml.org/lkml/2018/9/11/10
I am fine with this patchset going in (i reviewed it and tested it with
HMM on nouveau), Dan and Christoph did author the original code around
devm_memremap_pages() and thus ultimately they are the one who should
decide over GPL export or not.
Cheers,
Jérôme
next prev parent reply other threads:[~2018-10-12 18:14 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
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 ` Jerome Glisse [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-10-12 17:47 [PATCH v7 0/7] mm: Merge hmm into devm_memremap_pages, mark GPL-only Dan Williams
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