Messages in this thread Patch in this message | | | From | Vitaly Kuznetsov <> | Subject | [PATCH 2/3] memory_hotplug: add note about holding device_hotplug_lock and add_memory() | Date | Wed, 11 Feb 2015 16:44:21 +0100 |
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add_memory() is supposed to be run with device_hotplug_lock grabbed, otherwise it can race with e.g. device_online(). ACPI memory hotplug does that already but e.g. Hyper-V ballooning driver doesn't.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> --- mm/memory_hotplug.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 9fab107..41638eb 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1213,7 +1213,11 @@ int zone_for_memory(int nid, u64 start, u64 size, int zone_default) return zone_default; } -/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */ +/* + * NOTE: The caller must call lock_device_hotplug() to serialize hotplug + * and online/offline operations before this call. + * We are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG. + */ int __ref add_memory(int nid, u64 start, u64 size) { pg_data_t *pgdat = NULL; -- 1.9.3
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