Commit 06489cfb authored Dec 28, 2018 by Dan Williams Committed by Linus Torvalds Dec 28, 2018

mm, devm_memremap_pages: kill mapping "System RAM" support

Given the fact that devm_memremap_pages() requires a percpu_ref that is
torn down by devm_memremap_pages_release() the current support for mapping
RAM is broken.

Support for remapping "System RAM" has been broken since the beginning and
there is no existing user of this this code path, so just kill the support
and make it an explicit error.

This cleanup also simplifies a follow-on patch to fix the error path when
setting a devm release action for devm_memremap_pages_release() fails.

Link: http://lkml.kernel.org/r/154275557997.76910.14689813630968180480.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 808153e1

kernel/memremap.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -167,15 +167,12 @@ void devm_memremap_pages(struct device dev, struct dev_pagemap *pgmap)
		is_ram = region_intersects(align_start, align_size,
		IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);

		if (is_ram == REGION_MIXED) {
		WARN_ONCE(1, "%s attempted on mixed region %pr\n",
		__func__, res);
		if (is_ram != REGION_DISJOINT) {
		WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__,
		is_ram == REGION_MIXED ? "mixed" : "ram", res);
		return ERR_PTR(-ENXIO);
		}

		if (is_ram == REGION_INTERSECTS)
		return __va(res->start);

		if (!pgmap->ref)
		return ERR_PTR(-EINVAL);

Admin message