On Fri, 6 Jul 2018 16:53:11 -0700 Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > 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: "Jérôme 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). A resend would be good. And include the above info in the changelog. I can't say I'm terribly happy with the HMM situation. I was under the impression that a significant number of significant in-tree drivers would be using HMM but I've heard nothing since, apart from ongoing nouveau work, which will be perfectly happy with GPL-only exports. So yes, we should revisit the licensing situation and, if only nouveau will be using HMM we should revisit HMM's overall usefulness.
