mm: memory hotplug with an existing resource

Add add_memory_resource() to add memory using an existing "System RAM"
resource.  This is useful if the memory region is being located by
finding a free resource slot with allocate_resource().

Xen guests will make use of this in their balloon driver to hotplug
arbitrary amounts of memory in response to toolstack requests.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Tang Chen <tangchen@cn.fujitsu.com>

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 8f60e899b33c574b58be6d0a0d928c8f094941ea..2ea574ff97146446729ab6fbe66333e3df3117a0 100644 (file)
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -11,6 +11,7 @@ struct zone;
 struct pglist_data;
 struct mem_section;
 struct memory_block;
+struct resource;
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 
@@ -266,6 +267,7 @@ static inline void remove_memory(int nid, u64 start, u64 size) {}
 extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
                void *arg, int (*func)(struct memory_block *, void *));
 extern int add_memory(int nid, u64 start, u64 size);
+extern int add_memory_resource(int nid, struct resource *resource);
 extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default,
                bool for_device);
 extern int arch_add_memory(int nid, u64 start, u64 size, bool for_device);

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index aa992e2df58a42a6307a6324a3aa353e194d6f0f..0780d118d26e70d5cfc3a3e67ceca4915684a003 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1232,23 +1232,21 @@ int zone_for_memory(int nid, u64 start, u64 size, int zone_default,
 }
 
 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
-int __ref add_memory(int nid, u64 start, u64 size)
+int __ref add_memory_resource(int nid, struct resource *res)
 {
+       u64 start, size;
        pg_data_t *pgdat = NULL;
        bool new_pgdat;
        bool new_node;
-       struct resource *res;
        int ret;
 
+       start = res->start;
+       size = resource_size(res);
+
        ret = check_hotplug_memory_range(start, size);
        if (ret)
                return ret;
 
-       res = register_memory_resource(start, size);
-       ret = -EEXIST;
-       if (!res)
-               return ret;
-
        {       /* Stupid hack to suppress address-never-null warning */
                void *p = NODE_DATA(nid);
                new_pgdat = !p;
@@ -1300,13 +1298,28 @@ error:
        /* rollback pgdat allocation and others */
        if (new_pgdat)
                rollback_node_hotadd(nid, pgdat);
-       release_memory_resource(res);
        memblock_remove(start, size);
 
 out:
        mem_hotplug_done();
        return ret;
 }
+EXPORT_SYMBOL_GPL(add_memory_resource);
+
+int __ref add_memory(int nid, u64 start, u64 size)
+{
+       struct resource *res;
+       int ret;
+
+       res = register_memory_resource(start, size);
+       if (!res)
+               return -EEXIST;
+
+       ret = add_memory_resource(nid, res);
+       if (ret < 0)
+               release_memory_resource(res);
+       return ret;
+}
 EXPORT_SYMBOL_GPL(add_memory);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE