Merge branch 'slub/hotplug' into slab/urgent

include/linux/memory_hotplug.h

@@ -165,6 +165,12 @@ 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);
 

mm/memory_hotplug.c

@@ -409,6 +409,7 @@ 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;
@@ -421,6 +422,7 @@ 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;
 	}
 	/*
@@ -445,6 +447,7 @@ 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;
 	}
 
@@ -469,6 +472,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 
 	if (onlined_pages)
 		memory_notify(MEM_ONLINE, &arg);
+	unlock_memory_hotplug();
 
 	return 0;
 }

mm/slub.c

@@ -3797,7 +3797,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
 		}
 	}
 
-	down_read(&slub_lock);
+	lock_memory_hotplug();
 #ifdef CONFIG_SLUB_DEBUG
 	if (flags & SO_ALL) {
 		for_each_node_state(node, N_NORMAL_MEMORY) {
@@ -3838,7 +3838,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
 			x += sprintf(buf + x, " N%d=%lu",
 					node, nodes[node]);
 #endif
-	up_read(&slub_lock);
+	unlock_memory_hotplug();
 	kfree(nodes);
 	return x + sprintf(buf + x, "\n");
 }