linux-kernel - [PATCH 4.9 37/63] mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL

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Message-Id: <20190111131051.490237975@linuxfoundation.org>
Date:   Fri, 11 Jan 2019 15:14:40 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>,
        Christoph Hellwig <hch@....de>, Michal Hocko <mhocko@...e.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Balbir Singh <bsingharora@...il.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.9 37/63] mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL_GPL

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@...el.com>

commit 808153e1187fa77ac7d7dad261ff476888dcf398 upstream.

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.

Link: http://lkml.kernel.org/r/154275557457.76910.16923571232582744134.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Acked-by: Michal Hocko <mhocko@...e.com>
Cc: "Jérôme Glisse" <jglisse@...hat.com>
Cc: Balbir Singh <bsingharora@...il.com>
Cc: Logan Gunthorpe <logang@...tatee.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/memremap.c                 |    2 +-
 tools/testing/nvdimm/test/iomap.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -399,7 +399,7 @@ void *devm_memremap_pages(struct device
 	devres_free(page_map);
 	return ERR_PTR(error);
 }
-EXPORT_SYMBOL(devm_memremap_pages);
+EXPORT_SYMBOL_GPL(devm_memremap_pages);

 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 {
--- a/tools/testing/nvdimm/test/iomap.c
+++ b/tools/testing/nvdimm/test/iomap.c
@@ -114,7 +114,7 @@ void *__wrap_devm_memremap_pages(struct
 		return nfit_res->buf + offset - nfit_res->res.start;
 	return devm_memremap_pages(dev, res, ref, altmap);
 }
-EXPORT_SYMBOL(__wrap_devm_memremap_pages);
+EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);

 pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags)
 {