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-rw-r--r--include/linux/memory_hotplug.h6
-rw-r--r--mm/memory_hotplug.c4
2 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 31c237a00c48..12b9eb5a36c3 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -161,6 +161,12 @@ extern void register_page_bootmem_info_node(struct pglist_data *pgdat);
extern void put_page_bootmem(struct page *page);
#endif
+/*
+ * Lock for memory hotplug guarantees 1) all callbacks for memory hotplug
+ * notifier will be called under this. 2) offline/online/add/remove memory
+ * will not run simultaneously.
+ */
+
void lock_memory_hotplug(void);
void unlock_memory_hotplug(void);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2c6523af5473..83163c096a75 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -407,6 +407,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
int ret;
struct memory_notify arg;
+ lock_memory_hotplug();
arg.start_pfn = pfn;
arg.nr_pages = nr_pages;
arg.status_change_nid = -1;
@@ -419,6 +420,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
ret = notifier_to_errno(ret);
if (ret) {
memory_notify(MEM_CANCEL_ONLINE, &arg);
+ unlock_memory_hotplug();
return ret;
}
/*
@@ -443,6 +445,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
nr_pages, pfn);
memory_notify(MEM_CANCEL_ONLINE, &arg);
+ unlock_memory_hotplug();
return ret;
}
@@ -467,6 +470,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
if (onlined_pages)
memory_notify(MEM_ONLINE, &arg);
+ unlock_memory_hotplug();
return 0;
}

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