Commit 033fbae9 authored by Dan Williams's avatar Dan Williams
Browse files

mm: ZONE_DEVICE for "device memory" 



While pmem is usable as a block device or via DAX mappings to userspace
there are several usage scenarios that can not target pmem due to its
lack of struct page coverage. In preparation for "hot plugging" pmem
into the vmemmap add ZONE_DEVICE as a new zone to tag these pages
separately from the ones that are subject to standard page allocations.
Importantly "device memory" can be removed at will by userspace
unbinding the driver of the device.

Having a separate zone prevents allocation and otherwise marks these
pages that are distinct from typical uniform memory.  Device memory has
different lifetime and performance characteristics than RAM.  However,
since we have run out of ZONES_SHIFT bits this functionality currently
depends on sacrificing ZONE_DMA.

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Jerome Glisse <j.glisse@gmail.com>
[hch: various simplifications in the arch interface]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 012dcef3

arch/ia64/mm/init.c

+2 −2
Original line number Diff line number Diff line
@@ -645,7 +645,7 @@ mem_init (void) 
}



#ifdef CONFIG_MEMORY_HOTPLUG

int arch_add_memory(int nid, u64 start, u64 size)

int arch_add_memory(int nid, u64 start, u64 size, bool for_device)

{

	pg_data_t *pgdat;

	struct zone *zone;
@@ -656,7 +656,7 @@ int arch_add_memory(int nid, u64 start, u64 size) 
	pgdat = NODE_DATA(nid);



	zone = pgdat->node_zones +

		zone_for_memory(nid, start, size, ZONE_NORMAL);

		zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);

	ret = __add_pages(nid, zone, start_pfn, nr_pages);



	if (ret)

arch/powerpc/mm/mem.c

+2 −2
Original line number Diff line number Diff line
@@ -113,7 +113,7 @@ int memory_add_physaddr_to_nid(u64 start) 
}

#endif



int arch_add_memory(int nid, u64 start, u64 size)

int arch_add_memory(int nid, u64 start, u64 size, bool for_device)

{

	struct pglist_data *pgdata;

	struct zone *zone;
@@ -128,7 +128,7 @@ int arch_add_memory(int nid, u64 start, u64 size) 


	/* this should work for most non-highmem platforms */

	zone = pgdata->node_zones +

		zone_for_memory(nid, start, size, 0);

		zone_for_memory(nid, start, size, 0, for_device);



	return __add_pages(nid, zone, start_pfn, nr_pages);

}

arch/s390/mm/init.c

+1 −1
Original line number Diff line number Diff line
@@ -168,7 +168,7 @@ void __init free_initrd_mem(unsigned long start, unsigned long end) 
#endif



#ifdef CONFIG_MEMORY_HOTPLUG

int arch_add_memory(int nid, u64 start, u64 size)

int arch_add_memory(int nid, u64 start, u64 size, bool for_device)

{

	unsigned long zone_start_pfn, zone_end_pfn, nr_pages;

	unsigned long start_pfn = PFN_DOWN(start);

arch/sh/mm/init.c

+3 −2
Original line number Diff line number Diff line
@@ -485,7 +485,7 @@ void free_initrd_mem(unsigned long start, unsigned long end) 
#endif



#ifdef CONFIG_MEMORY_HOTPLUG

int arch_add_memory(int nid, u64 start, u64 size)

int arch_add_memory(int nid, u64 start, u64 size, bool for_device)

{

	pg_data_t *pgdat;

	unsigned long start_pfn = start >> PAGE_SHIFT;
@@ -496,7 +496,8 @@ int arch_add_memory(int nid, u64 start, u64 size) 


	/* We only have ZONE_NORMAL, so this is easy.. */

	ret = __add_pages(nid, pgdat->node_zones +

			zone_for_memory(nid, start, size, ZONE_NORMAL),

			zone_for_memory(nid, start, size, ZONE_NORMAL,

			for_device),

			start_pfn, nr_pages);

	if (unlikely(ret))

		printk("%s: Failed, __add_pages() == %d\n", __func__, ret);

arch/tile/mm/init.c

+1 −1
Original line number Diff line number Diff line
@@ -863,7 +863,7 @@ void __init mem_init(void) 
 * memory to the highmem for now.

 */

#ifndef CONFIG_NEED_MULTIPLE_NODES

int arch_add_memory(u64 start, u64 size)

int arch_add_memory(u64 start, u64 size, bool for_device)

{

	struct pglist_data *pgdata = &contig_page_data;

	struct zone *zone = pgdata->node_zones + MAX_NR_ZONES-1;

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