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authorBadari Pulavarty <pbadari@us.ibm.com>2008-07-23 21:28:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-24 10:47:21 -0700
commit5c755e9fd813810680abd56ec09a5f90143e815b (patch)
tree1686c0666f6bd630441957a53c546d90b0f61723 /drivers/base/memory.c
parent2f7f24eca31c4fc2fdb134b2ef743ccd67cfb9a9 (diff)
downloadop-kernel-dev-5c755e9fd813810680abd56ec09a5f90143e815b.zip
op-kernel-dev-5c755e9fd813810680abd56ec09a5f90143e815b.tar.gz
memory-hotplug: add sysfs removable attribute for hotplug memory remove
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 <pbadari@us.ibm.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/base/memory.c')
-rw-r--r--drivers/base/memory.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 4d4e0e7..855ed1a 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -101,6 +101,21 @@ static ssize_t show_mem_phys_index(struct sys_device *dev,
}
/*
+ * 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.
*/
static ssize_t show_mem_state(struct sys_device *dev,
@@ -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;
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