kmemleak: Add kmemleak_alloc callback from alloc_large_system_hash

The alloc_large_system_hash function is called from various places in
the kernel and it contains pointers to other allocated structures. It
therefore needs to be traced by kmemleak.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

mm/page_alloc.c

@@ -46,6 +46,7 @@
 #include <linux/page-isolation.h>
 #include <linux/page_cgroup.h>
 #include <linux/debugobjects.h>
+#include <linux/kmemleak.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -4546,6 +4547,16 @@ void *__init alloc_large_system_hash(const char *tablename,
 	if (_hash_mask)
 		*_hash_mask = (1 << log2qty) - 1;
 
+	/*
+	 * If hashdist is set, the table allocation is done with __vmalloc()
+	 * which invokes the kmemleak_alloc() callback. This function may also
+	 * be called before the slab and kmemleak are initialised when
+	 * kmemleak simply buffers the request to be executed later
+	 * (GFP_ATOMIC flag ignored in this case).
+	 */
+	if (!hashdist)
+		kmemleak_alloc(table, size, 1, GFP_ATOMIC);
+
 	return table;
 }