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Commit b584c254 authored by Oliver O'Halloran's avatar Oliver O'Halloran Committed by Michael Ellerman
Browse files

powerpc/vmemmap: Add altmap support 



Adds support to powerpc for the altmap feature of ZONE_DEVICE memory. An
altmap is a driver provided region that is used to provide the backing
storage for the struct pages of ZONE_DEVICE memory. In situations where
large amount of ZONE_DEVICE memory is being added to the system the
altmap reduces pressure on main system memory by allowing the mm/
metadata to be stored on the device itself rather in main memory.

Reviewed-by: default avatarBalbir Singh <bsingharora@gmail.com>
Signed-off-by: default avatarOliver O'Halloran <oohall@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent d7d9b612

arch/powerpc/mm/init_64.c

+13 −2
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#include <linux/slab.h>

#include <linux/of_fdt.h>

#include <linux/libfdt.h>

#include <linux/memremap.h>



#include <asm/pgalloc.h>

#include <asm/page.h>
@@ -192,13 +193,17 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 
	pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);



	for (; start < end; start += page_size) {

		struct vmem_altmap *altmap;

		void *p;

		int rc;



		if (vmemmap_populated(start, page_size))

			continue;



		p = vmemmap_alloc_block(page_size, node);

		/* altmap lookups only work at section boundaries */

		altmap = to_vmem_altmap(SECTION_ALIGN_DOWN(start));



		p =  __vmemmap_alloc_block_buf(page_size, node, altmap);

		if (!p)

			return -ENOMEM;
@@ -263,6 +268,8 @@ void __ref vmemmap_free(unsigned long start, unsigned long end) 


	for (; start < end; start += page_size) {

		unsigned long nr_pages, addr;

		struct vmem_altmap *altmap;

		struct page *section_base;

		struct page *page;



		/*
@@ -278,9 +285,13 @@ void __ref vmemmap_free(unsigned long start, unsigned long end) 
			continue;



		page = pfn_to_page(addr >> PAGE_SHIFT);

		section_base = pfn_to_page(vmemmap_section_start(start));

		nr_pages = 1 << page_order;



		if (PageReserved(page)) {

		altmap = to_vmem_altmap((unsigned long) section_base);

		if (altmap) {

			vmem_altmap_free(altmap, nr_pages);

		} else if (PageReserved(page)) {

			/* allocated from bootmem */

			if (page_size < PAGE_SIZE) {

				/*

arch/powerpc/mm/mem.c

+13 −3
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <linux/hugetlb.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <linux/memremap.h>



#include <asm/pgalloc.h>

#include <asm/prom.h>
@@ -159,11 +160,20 @@ int arch_remove_memory(u64 start, u64 size) 
{

	unsigned long start_pfn = start >> PAGE_SHIFT;

	unsigned long nr_pages = size >> PAGE_SHIFT;

	struct zone *zone;

	struct vmem_altmap *altmap;

	struct page *page;

	int ret;



	zone = page_zone(pfn_to_page(start_pfn));

	ret = __remove_pages(zone, start_pfn, nr_pages);

	/*

	 * If we have an altmap then we need to skip over any reserved PFNs

	 * when querying the zone.

	 */

	page = pfn_to_page(start_pfn);

	altmap = to_vmem_altmap((unsigned long) page);

	if (altmap)

		page += vmem_altmap_offset(altmap);



	ret = __remove_pages(page_zone(page), start_pfn, nr_pages);

	if (ret)

		return ret;