kmemleak: Add support for memory hotplug

Ensure that memory hotplug can co-exist with kmemleak
by taking the hotplug lock before scanning the memory
banks.

Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 15c5030..c833add 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -100,6 +100,7 @@
 
 #include <linux/kmemcheck.h>
 #include <linux/kmemleak.h>
+#include <linux/memory_hotplug.h>
 
 /*
  * Kmemleak configuration and common defines.
@@ -1292,9 +1293,9 @@
 #endif
 
 	/*
-	 * Struct page scanning for each node. The code below is not yet safe
-	 * with MEMORY_HOTPLUG.
+	 * Struct page scanning for each node.
 	 */
+	lock_memory_hotplug();
 	for_each_online_node(i) {
 		pg_data_t *pgdat = NODE_DATA(i);
 		unsigned long start_pfn = pgdat->node_start_pfn;
@@ -1313,6 +1314,7 @@
 			scan_block(page, page + 1, NULL, 1);
 		}
 	}
+	unlock_memory_hotplug();
 
 	/*
 	 * Scanning the task stacks (may introduce false negatives).