Re: [PATCH v3 7/8] mm, hmm: Mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL

[Dan Williams]

On Mon, Jun 18, 2018 at 11:05 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> The routines hmm_devmem_add(), and hmm_devmem_add_resource() are
> now wrappers around the functionality provided by devm_memremap_pages() to
> inject a dev_pagemap instance and hook page-idle events. The
> devm_memremap_pages() interface is base infrastructure for HMM which has
> more and deeper ties into the kernel memory management implementation
> than base ZONE_DEVICE.
>
> Originally, the HMM page structure creation routines copied the
> devm_memremap_pages() code and reused ZONE_DEVICE. A cleanup to unify
> the implementations was discussed during the initial review:
> http://lkml.iu.edu/hypermail/linux/kernel/1701.2/00812.html
>
> Given that devm_memremap_pages() is marked EXPORT_SYMBOL_GPL by its
> authors and the hmm_devmem_{add,add_resource} routines are simple
> wrappers around that base, mark these routines as EXPORT_SYMBOL_GPL as
> well.
>
> Cc: "JÃrÃme Glisse" <jglisse@xxxxxxxxxx>
> Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Currently OpenAFS is blocked from compiling with the 4.18 series due
to the current state of put_page() inadvertently pulling in GPL-only
symbols. This series, "PATCH v3 0/8] mm: Rework hmm to use
devm_memremap_pages and other fixes" corrects that situation and
corrects HMM's usage of EXPORT_SYMBOL_GPL.

If HMM wants to export functionality to out-of-tree proprietary
drivers it should do so without consuming GPL-only exports, or
consuming internal-only public functions in its exports.

In addition to duplicating devm_memremap_pages(), that should have
been EXPORT_SYMBOL_GPL from the beginning, it is also exporting /
consuming these GPL-only symbols via HMM's EXPORT_SYMBOL entry points.

    mmu_notifier_unregister_no_release
    percpu_ref
    region_intersects
    __class_create

Those entry points also consume / export functionality that is
currently not exported to any other driver.

    alloc_pages_vma
    walk_page_range

Andrew, please consider applying this v3 series to fix this up (let me
know if you need a resend).