x86, pat: Proper init of memtype subtree_max_end

subtree_max_end that was recently added to struct memtype was not getting
properly initialized resulting in

WARNING: kmemcheck: Caught 64-bit read from uninitialized memory
in memtype_rb_augment_cb()
reported here
https://bugzilla.kernel.org/show_bug.cgi?id=16092

This change fixes the problem.
Reported-by: Christian Casteyde <casteyde.christian@free.fr>
Tested-by: Christian Casteyde <casteyde.christian@free.fr>
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
LKML-Reference: <1276217101-11515-1-git-send-email-venki@google.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>

arch/x86/mm/pat.c

@@ -302,7 +302,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
 		return -EINVAL;
 	}
 
-	new  = kmalloc(sizeof(struct memtype), GFP_KERNEL);
+	new  = kzalloc(sizeof(struct memtype), GFP_KERNEL);
 	if (!new)
 		return -ENOMEM;
 

arch/x86/mm/pat_rbtree.c

@@ -226,6 +226,7 @@ int rbt_memtype_check_insert(struct memtype *new, unsigned long *ret_type)
 		if (ret_type)
 			new->type = *ret_type;
 
+		new->subtree_max_end = new->end;
 		memtype_rb_insert(&memtype_rbroot, new);
 	}
 	return err;