Page migration: Do not accept invalid nodes as a target nodeset

Page migration currently does not check if the target of the move contains
nodes that that are invalid and may try to allocate from invalid nodes if
these are specified leading to oopses.

Return -EINVAL if a node is specified that is not known to have memory.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 mm/mempolicy.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6.23-rc3-mm1/mm/mempolicy.c
===================================================================
--- linux-2.6.23-rc3-mm1.orig/mm/mempolicy.c	2007-08-23 12:26:49.000000000 -0700
+++ linux-2.6.23-rc3-mm1/mm/mempolicy.c	2007-08-23 14:44:50.000000000 -0700
@@ -965,6 +965,11 @@ asmlinkage long sys_migrate_pages(pid_t 
 		goto out;
 	}
 
+	if (!nodes_subset(new, node_states[N_HIGH_MEMORY])) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	err = security_task_movememory(task);
 	if (err)
 		goto out;