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memory-hotplug: add sysfs removable attribute for hotplug memory remove

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Memory may be hot-removed on a per-memory-block basis, particularly on
POWER where the SPARSEMEM section size often matches the memory-block
size.  A user-level agent must be able to identify which sections of
memory are likely to be removable before attempting the potentially
expensive operation.  This patch adds a file called "removable" to the
memory directory in sysfs to help such an agent.  In this patch, a memory
block is considered removable if;

o It contains only MOVABLE pageblocks
o It contains only pageblocks with free pages regardless of pageblock type

On the other hand, a memory block starting with a PageReserved() page will
never be considered removable.  Without this patch, the user-agent is
forced to choose a memory block to remove randomly.

Sample output of the sysfs files:

./memory/memory0/removable: 0
./memory/memory1/removable: 0
./memory/memory2/removable: 0
./memory/memory3/removable: 0
./memory/memory4/removable: 0
./memory/memory5/removable: 0
./memory/memory6/removable: 0
./memory/memory7/removable: 1
./memory/memory8/removable: 0
./memory/memory9/removable: 0
./memory/memory10/removable: 0
./memory/memory11/removable: 0
./memory/memory12/removable: 0
./memory/memory13/removable: 0
./memory/memory14/removable: 0
./memory/memory15/removable: 0
./memory/memory16/removable: 0
./memory/memory17/removable: 1
./memory/memory18/removable: 1
./memory/memory19/removable: 1
./memory/memory20/removable: 1
./memory/memory21/removable: 1
./memory/memory22/removable: 1

Signed-off-by: Badari Pulavarty <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Badari Pulavarty 2008-07-23 21:28:19 -07:00 • committed by Linus Torvalds
commit 5c755e9fd8
4 changed files with 115 additions and 0 deletions
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19
drivers/base/memory.c
View file

@ -100,6 +100,21 @@ static ssize_t show_mem_phys_index(struct sys_device *dev,
return sprintf(buf, "%08lx\n", mem->phys_index);
}
/*
* Show whether the section of memory is likely to be hot-removable
*/
static ssize_t show_mem_removable(struct sys_device *dev, char *buf)
{
unsigned long start_pfn;
int ret;
struct memory_block *mem =
container_of(dev, struct memory_block, sysdev);
start_pfn = section_nr_to_pfn(mem->phys_index);
ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
return sprintf(buf, "%d\n", ret);
}
/*
* online, offline, going offline, etc.
*/
@ -262,6 +277,7 @@ static ssize_t show_phys_device(struct sys_device *dev,
static SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
static SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
static SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
static SYSDEV_ATTR(removable, 0444, show_mem_removable, NULL);
#define mem_create_simple_file(mem, attr_name) \
sysdev_create_file(&mem->sysdev, &attr_##attr_name)
@ -350,6 +366,8 @@ static int add_memory_block(unsigned long node_id, struct mem_section *section,
ret = mem_create_simple_file(mem, state);
if (!ret)
ret = mem_create_simple_file(mem, phys_device);
if (!ret)
ret = mem_create_simple_file(mem, removable);
return ret;
}
@ -394,6 +412,7 @@ int remove_memory_block(unsigned long node_id, struct mem_section *section,
mem_remove_simple_file(mem, phys_index);
mem_remove_simple_file(mem, state);
mem_remove_simple_file(mem, phys_device);
mem_remove_simple_file(mem, removable);
unregister_memory(mem, section);
return 0;