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author | Toshi Kani <toshi.kani@hp.com> | 2013-09-11 14:21:50 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:57:41 -0700 |
commit | 0f1cfe9d0d06fe44c2b310401d2db101968e8c58 (patch) | |
tree | 2cc5633a41b73adcd6408509c612211cdc1c506c /mm | |
parent | 27356f54c8c32609ff45b4ed333bb64fb2eef374 (diff) | |
download | op-kernel-dev-0f1cfe9d0d06fe44c2b310401d2db101968e8c58.zip op-kernel-dev-0f1cfe9d0d06fe44c2b310401d2db101968e8c58.tar.gz |
mm/hotplug: remove stop_machine() from try_offline_node()
lock_device_hotplug() serializes hotplug & online/offline operations. The
lock is held in common sysfs online/offline interfaces and ACPI hotplug
code paths.
And here are the code paths:
- CPU & Mem online/offline via sysfs online
store_online()->lock_device_hotplug()
- Mem online via sysfs state:
store_mem_state()->lock_device_hotplug()
- ACPI CPU & Mem hot-add:
acpi_scan_bus_device_check()->lock_device_hotplug()
- ACPI CPU & Mem hot-delete:
acpi_scan_hot_remove()->lock_device_hotplug()
try_offline_node() off-lines a node if all memory sections and cpus are
removed on the node. It is called from acpi_processor_remove() and
acpi_memory_remove_memory()->remove_memory() paths, both of which are in
the ACPI hotplug code.
try_offline_node() calls stop_machine() to stop all cpus while checking
all cpu status with the assumption that the caller is not protected from
CPU hotplug or CPU online/offline operations. However, the caller is
always serialized with lock_device_hotplug(). Also, the code needs to be
properly serialized with a lock, not by stopping all cpus at a random
place with stop_machine().
This patch removes the use of stop_machine() in try_offline_node() and
adds comments to try_offline_node() and remove_memory() that
lock_device_hotplug() is required.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/memory_hotplug.c | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 247d666..d595606 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1695,9 +1695,8 @@ static int is_memblock_offlined_cb(struct memory_block *mem, void *arg) return ret; } -static int check_cpu_on_node(void *data) +static int check_cpu_on_node(pg_data_t *pgdat) { - struct pglist_data *pgdat = data; int cpu; for_each_present_cpu(cpu) { @@ -1712,10 +1711,9 @@ static int check_cpu_on_node(void *data) return 0; } -static void unmap_cpu_on_node(void *data) +static void unmap_cpu_on_node(pg_data_t *pgdat) { #ifdef CONFIG_ACPI_NUMA - struct pglist_data *pgdat = data; int cpu; for_each_possible_cpu(cpu) @@ -1724,10 +1722,11 @@ static void unmap_cpu_on_node(void *data) #endif } -static int check_and_unmap_cpu_on_node(void *data) +static int check_and_unmap_cpu_on_node(pg_data_t *pgdat) { - int ret = check_cpu_on_node(data); + int ret; + ret = check_cpu_on_node(pgdat); if (ret) return ret; @@ -1736,11 +1735,18 @@ static int check_and_unmap_cpu_on_node(void *data) * the cpu_to_node() now. */ - unmap_cpu_on_node(data); + unmap_cpu_on_node(pgdat); return 0; } -/* offline the node if all memory sections of this node are removed */ +/** + * try_offline_node + * + * Offline a node if all memory sections and cpus of the node are removed. + * + * NOTE: The caller must call lock_device_hotplug() to serialize hotplug + * and online/offline operations before this call. + */ void try_offline_node(int nid) { pg_data_t *pgdat = NODE_DATA(nid); @@ -1766,7 +1772,7 @@ void try_offline_node(int nid) return; } - if (stop_machine(check_and_unmap_cpu_on_node, pgdat, NULL)) + if (check_and_unmap_cpu_on_node(pgdat)) return; /* @@ -1803,6 +1809,13 @@ void try_offline_node(int nid) } EXPORT_SYMBOL(try_offline_node); +/** + * remove_memory + * + * NOTE: The caller must call lock_device_hotplug() to serialize hotplug + * and online/offline operations before this call, as required by + * try_offline_node(). + */ void __ref remove_memory(int nid, u64 start, u64 size) { int ret; |