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From: Dan Williams <dan.j.williams@intel.com>
To: akpm@linux-foundation.org
Cc: "Michal Hocko" <mhocko@suse.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Christoph Hellwig" <hch@lst.de>,
	alexander.h.duyck@intel.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 1/7] mm, devm_memremap_pages: Mark devm_memremap_pages() EXPORT_SYMBOL_GPL
Date: Wed, 12 Sep 2018 19:22:06 -0700
Message-ID: <153680532635.453305.11297363695024516117.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <153680531988.453305.8080706591516037706.stgit@dwillia2-desk3.amr.corp.intel.com>

devm_memremap_pages() is a facility that can create struct page entries
for any arbitrary range and give drivers the ability to subvert core
aspects of page management.

Specifically the facility is tightly integrated with the kernel's memory
hotplug functionality. It injects an altmap argument deep into the
architecture specific vmemmap implementation to allow allocating from
specific reserved pages, and it has Linux specific assumptions about
page structure reference counting relative to get_user_pages() and
get_user_pages_fast(). It was an oversight and a mistake that this was
not marked EXPORT_SYMBOL_GPL from the outset.

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.

Cc: Michal Hocko <mhocko@suse.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 kernel/memremap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 5b8600d39931..f95c7833db6d 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -283,7 +283,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	pgmap_radix_release(res, pgoff);
 	return ERR_PTR(error);
 }
-EXPORT_SYMBOL(devm_memremap_pages);
+EXPORT_SYMBOL_GPL(devm_memremap_pages);
 
 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 {


  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-13  2:22 [PATCH v5 0/7] mm: Merge hmm into devm_memremap_pages, mark GPL-only Dan Williams
2018-09-13  2:22 ` Dan Williams [this message]
2018-09-13 16:25   ` [PATCH v5 1/7] mm, devm_memremap_pages: Mark devm_memremap_pages() EXPORT_SYMBOL_GPL Logan Gunthorpe
2018-09-13  2:22 ` [PATCH v5 2/7] mm, devm_memremap_pages: Kill mapping "System RAM" support Dan Williams
2018-09-13 16:10   ` Logan Gunthorpe
2018-09-14 13:14   ` Christoph Hellwig
2018-09-14 17:40     ` Dan Williams
2018-09-18 20:28   ` Jerome Glisse
2018-09-13  2:22 ` [PATCH v5 3/7] mm, devm_memremap_pages: Fix shutdown handling Dan Williams
2018-09-14 13:16   ` Christoph Hellwig
2018-09-14 17:25     ` Dan Williams
2018-09-18 20:28   ` Jerome Glisse
2018-09-13  2:22 ` [PATCH v5 4/7] mm, devm_memremap_pages: Add MEMORY_DEVICE_PRIVATE support Dan Williams
2018-09-14 13:18   ` Christoph Hellwig
2018-09-18 20:34   ` Jerome Glisse
2018-09-13  2:22 ` [PATCH v5 5/7] mm, hmm: Use devm semantics for hmm_devmem_{add, remove} Dan Williams
2018-09-14 13:18   ` Christoph Hellwig
2018-09-14 14:16     ` Jerome Glisse
2018-09-18 20:34   ` Jerome Glisse
2018-09-13  2:22 ` [PATCH v5 6/7] mm, hmm: Replace hmm_devmem_pages_create() with devm_memremap_pages() Dan Williams
2018-09-18 20:35   ` Jerome Glisse
2018-09-19  1:24   ` Balbir Singh
2018-09-13  2:22 ` [PATCH v5 7/7] mm, hmm: Mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL Dan Williams

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